Grant/Remove Course Progress or Completion

We have courses with prerequisites, but some of our users have previously completed most of the courses in live training or in a different LMS. Without making the user go through the content again or take a "test out" quiz, is there a way to grant the user completion of that course?

Along with that, is there a way to reset the course completion for a user if we find they didn't actually complete the course or they simply need to take it again? We have some users in that situation, and the only thing we can think of is to delete the user and re-add them... but then we lose all of their other progress that we needed to keep, so it's not a viable solution.

Basically, we need to know if there is some sort of manager, admin, etc. ability to grant or revoke course credit without any action from the user.

Thank you for your help!