This document has not been formally reviewed for accuracy and is provided "as is" for your convenience.
Summary
Question
Disabling Multi-Tenancy is not allowed since version 9.41
Now disable Multitenancy option is available on AM 9.63
Customers are unaware that enabling MT is an irreversible change in old versions.
If MT is check but wasn't configured, only admin user can access to the tables even if there are users with admin rights, once MT is configure the rest of the users can create, modify or delete succesfully.
Answer
The workaround is to implement Multi-Tenancy for single organization. However, this requires careful implementation of MT, not a good solution for single organization.
Another fix is a restore of the database just in case that you have one backup before MT was enable.
Disable Multitenancy option is available on AM 9.63