Revoking POA against promoter of property

We have an undivided ancestral property in Kolkata (south). We are five shareholders of the property. one part (50%) consists of my fast cousin's (now deceased) family and the other (50%) part is shared equally by me and my brother. Recently we have decided to enter into a joint venture agreement with a local promoter on 50-50 basis. Owners allocation of 50% will be like, first part will get 25% and we the second part will get 25% of share. While the first part of the owners have decided to secure a flat, we (two brothers) have decided to sale off our part. The developer has agreed to purchase our portion. now the developer is entering into an agreement of paying a token amount at the time of signing off the agreement, while the balance amount to be released after the sanction of plan. They also want us to sign into a POA for execution of building construction and sale of the builder's allocated 50%. The builders have also consoled us saying that in case of failing to delaying the payment, we can always withdraw the POA and stop the construction work. kindly advise if this is true that in any later date owners can withdraw the POA.