Hello Cruz,
To address this issue in Odoo 16, you can follow these steps:

1. Remove the Custom Module: Ensure that the custom module you want to remove is uninstalled from your Odoo instance.
2. Update the Module List: Go to Settings > Modules > Update Modules List and update the list to reflect the removal of the custom module.
   
3. Remove Actions and Menu Items: Go to Settings > Technical > Actions > Actions.Search for any actions related to the custom module. Delete these actions by selecting them and clicking on the "Delete" button. Go to Settings > Technical > User Interface > Menu Items. Search for any menu items related to the custom module. Delete these menu items by selecting them and clicking on the "Delete" button.
4. Update Access Rights: Go to Settings > Users & Companies > Groups. Search for any groups related to the custom module. Remove access rights for these groups by selecting the groups and editing their access rights.
   
5. Restart Odoo Server: After making these changes, restart your Odoo server to apply the changes.

These steps should remove the actions and menu items associated with the custom module and ensure that it is no longer accessible to users.

Hope it helps

Hi,
Normally when a module is uninstalled all the records added from that module will be removed from the db during the uninstallation process.

Can you confirm the installation status of the module is uninstalled ?

Thanks