Yes, legal documents can be amended. If you wish to make a change to a legal document, ensure that all parties agree before making any amendments.
If you are going to make a small change to a document, like a correction or a deletion, you can use an Contract Addendum to both put the desired change in writing and to ensure that all parties are aware of the adjustment.
If you need to make extensive changes, it is recommended that you create a new version of your contract.