Deleting agreements from Library

I've updated my standard consulting agreements and would like to upload them into my library, but then the titles will conflict with those already in the library. For instance "5 Months Consulting" might be the old contract, but when I upload the new version of my consulting agreement for five months, it will have to be like "5 Months Consulting New"... then what happens if I have to change the agreement again? There must be a way to delete the old agreements from the library, while leaving the signed contracts in place even if they used that agreement template in the library...?