You can file a case of breach of contract or suit for specific performance against him with prayers of cancellation of the deed

1) issue legal notice to purchaser to execute cancellation deed as token money has been refunded to him on account of his inability to make balance payment 

2) you cannot sell flat to another purchaser till deed of cancellation is executed by earlier buyer 

I advise you to file a case of breach of contract or specific performance against the previous buyer for executing the the cancellation deed,

you can also make a police complaint,

but first of all send legal notice to the previous buyer to execute cancellation deed which will be fructify for you.

Sir send a legal notice to buyer to either make full payments and get property registered along with the delay interest as he has failed to make payments as agreed under the agreement for the property. In case he does not have funds for same as him to come forward and sign cancellation of the agreement and he can take refund of amount as per the agreement.

In case on notice he doesn't turn up for cancellation then a suit for specific performance against him has to be filed. 

If time was the essence of this sale agreement, and the buyer failed to perform his part of obligations within the assigned time, you are free to unilaterally cancel this agreement by way of sending a cancellation notice to this buyer through a lawyer.

The sale deed must be having a clause in case the buyer is not able to pay the full amount within the stipulated time. In case that us missing then too..you should approach the RERA tribunal for redressal of your grievances.

Regards 

Sell it to another buyer as the first buyer has not gone for a sale deed as per terms of the agreement then money paid through registered agreement is not required to be refunded if not obeyed in its terms and conditions.

Dear Sir,

- Legal notice to be issued through lawyer initially-

- U/s 15 of "Specific Performance Act," if you come to the category to obtain the specific performance act you can claim the right (In your case you seem authorize )

- U/s 20 (3) Substituted performance of contract of "Specific Performance Act"., You can take legal action against him.

- Do hire a lawyer to suggest better as per agreement signed before and after cancellation of apartment sales clause.

Regards

Vivek Arya

Issue a legal notice through an advocate and file a civil suit breach of contract. 

A contract on breach of any term and condition by either party can be cancelled by the other party unilaterally by intimating the party in default accordingly. There is no need of any cancellation deed to be signed by the defaulting party.

Hi, 

In the said circumstances, you may give a newspaper publications as well as legal notice to the earlier buyer reflecting his default and if he does not respond, go ahead for selling the property to new buyer. 

Dear Client,

Do you have refund receipt ? Agreement already cancelled by conduct of parties.  You can sell to third party.

If you have refunded the booking amount in full and have obtained a receipt to that effect from the buyer while communicating his decision to cancel the sale agreement, you may issue a legal notice to the buyer instructing him to appear before the concerned registrar's office on a date and time convenient  to both to jointly execute a registered cancellation deed, filing which you may proceed unilaterally to cancel the same at his costs and consequences.

You may discuss with your advocate and proceed with the steps suggested or any other suggestion made by yor advocate which may be more simpler or proper accordions to the  prevailing circumstances 

Dear Sir,

It is better to file Specific performance case in Civil Court against the buyer.

Yes, you can cancel the agreement to sell as the purchaser has failed to comply with the terms and condition of the agreement. ... Thus, you can proceed to cancel the agreement by issuing a legal notice to him through your lawyer.

In real estate terms, specific performance means when either the buyer or the seller wants to complete the sale under the agreed terms and conditions in the agreement to sell. A buyer or seller who wants to compel the recalcitrant party to honour the agreement under already agreed-upon terms can plead injunction by seeking a court order to complete the sale. However, the court has the sole discretion to order a real estate sale through specific performance. 

1. As per the information mentioned in the present query, makes it clear that you have been going so legally that no one can do anything which may go against your interest and I really appreciate the awareness that you showed in the above mentioned situation.
2. You should give him a legal notice for executing the same and wait for 15 days stating the same time period in the legal notice to comply what they written cancellation letter.
3. If they don’t do then you may have to approach the court of law seeking performance of the same document which has been signed by him, and also pray for the delay and litigation cost front him as he is at fault, not you.