Seller Financing. Can buyer renovate property before payoff?

Is it possible in a seller financed transaction, for the buyer to start renovating the property or even do a tear down before the terms of the purchase agreement have been completed (seller totally paid off)?

A- If YES, what recourse does the seller have, if buyer defaults, besides foreclosing?

B- If NO, how can a flipper start working on the deal ASAP?

(It may have been asked before on another forum, if so my apologies.)

Thank you

Eduardo