It is necessary to peruse the trust deed to advice 

The settlor, that is, the person who had initially transferred property and created a trust provided there were powers of revocation reserved by him as per the trust deed. The settlor may exercise the power of revocation and revoke such trust by way of registered deed of revocation.

See if in the trust deed father has rights to revoke or modify the trust then he cando same without the consent. Further in the case it is better to pursue the trust deed and power alloted to you under same.

for dissolving the trust you will need permission of the Charity Commissioner

The trust appears to be revocable in nature.

However the fate of the trust and the mode and manner of its dissolution , if any , must be mentioned in the trust deed itself.In other words without seeing the trust deed it is very difficult to advise whether in this way the trust can be dissolved and you will get back the land.

Dear Client,

Dissolution of trust is in the hand of trustee or trust registrar if he/she finds than purpose of trust not left meaningful or actual existence of trust is vague and just status left.

Change of position shall be informed to you and registrar.

1. Trust can be dissolved ONLY with the written permission of the local competent authority (charity commissioner).

2. A Trust must have MINIMUM of two trustees, else the Trust becomes defunct, for any & all purposes.

Keep Smiling .... Hemant Agarwal

You should peruse the terms and conditions of the trust from the trust deed to find if there are any such clause authorising the trustee to do the desired acts without the knowledge of other trust members.

Also you may see the clause invoking cancelaltion/dissolution  of trust in the same deed.

Thus without perusing the contents of the trust deed, it cannot be concretely opined anything with tregard to your query.

• 
  fulfillment of purpose: When the purpose is completely fulfilled, e.g., a settlor can stipulate that the trust shall last until the marriage of the beneficiary. In such case, the trust will get dissolved once the marriage gets solemnised.

• 
  Dissolution of trust: Where the trust is for the payment of the debts of the author of the trust and has not been communicated to the creditors at the pleasure of the author of the trust, the author can dissolve the trust, e.g., A conveys some property to B in trust to sell the same and pay out of the proceeds the claims of A’s creditors. If no communication has been made to the creditors, A may revoke the trust.

On the dissolution of the trust under one or more of the aforesaid circumstances, the ‘Trust Dissolution Deed’  should be made and be registered.

No he can't change its illegal