Unable to add removed user back to on-prem sentry

I removed a user from our on-prem sentry system and need to enter them back in. I send the invite, but they are unable to complete as it indicates an existing user account. I have checked and only see the pending invite. Does this data clean up after a period of time or is their a process that I can get this user back in. Appreciate any and all assistance. Sentry version - Sentry 21.4.15eee198