Need to protect formula but allow input

Thank you. I know how to protect and lock. However I have one column that allows the user to input in the colum cells and the cells have a formula. If the user input incorrect info they need to be abe to hit delete without deleting the formula. If I put the formula in another cell that I could lock and referenced it to the cells that can be used. Would that work and if so, how would I do that?