When you delete a user, his or her documents will stay in PandaDoc and be available to any user that has access to other user's documents. By default users with Manager or Admin roles can access all documents within the account. Click here to learn more about user roles
The document can still be signed by the recipient if they have not been signed yet. However, any documents that the removed user has not yet signed can only be signed from that particular account.
All email notifications about sent documents will go to this deleted user's email address, so we would recommend duplicating any unfinished documents to your account (on the removed user's end - not ones that only need to be completed by the recipient). In this case, the documents will need to be resent to the recipient.