An attorney would clearly need to be called for anyone to try to invoke that right, whether it be about financing or something else. That attorney NOT being the actual buyer or seller, as it was in my case, would be best. :)
Form 22A (Financing Addendum to purchase and sale agreement) has a "Seller's Right to Terminate" paragraph. This addendum is primarily a protection for the buyer so that if the buyer is unable to obtain financing the contract to purchase the property can be terminated and the buyer will be entitled to get back his/her earnest money.
If no time frame is filled in in the Seller's Right to Terminate paragraph then it defaults to 30 days. This doesn't mean that that seller can decide to terminate the contract for any reason as long as it is within the 30 days. It means that the seller is willing to give buyer 30 days to find financing before moving on. After 30 days (or whatever the number filled in is) the seller has the right to terminate the contract. So a smaller number in this spot is better for the seller and a larger number is better for the buyer.
A seller might receive another offer after entering mutual acceptance with a buyer, and it could be a more appealing offer so the seller may decide to terminate an existing contract with with a buyer if he/she has yet to obtain financing and the time period set forth in form 22A, paragraph 2 has passed.
Sellers can give notice, after a set time, to Buyer to remove the financing condition or the offer is terminated.
This is in place to force the buyer to get his/her/their loan complete.
If a seller feels the buyer is not going to be able to close, this clause gets the buyer out of first position so seller may sell the property to a buyer who is able to close.
If the buyer waives the financing condition then the buyer risks buyer's EM or other such remedy as stated in the contract.
In my 30 years of RE I have only advised the Seller to use this a couple of times.
I believe you are referring to a paragraph on 22A, the financing contingency. If this is the case, the seller can give written notice to the buyer to waive the financing contingency, which puts your earnest money at risk if the loan is not approved, or the seller could terminate the deal.
Without written notice, this contingency is not automatically waived and it's rarely in the seller's interest to start over if you are close to finalizing the deal.
Since I'm guessing here, I want you to take your contract to your agent for a better explanation or to an attorney.
If this is a serious issue you need to hire an attorney to understand and explain this contractual term. You should not rely on a blog frequented by agents.