You can do this by directly doing some "cleanups" inside the database.
Get the ID number of this user, and clear the field "restricted_to" inside table "items" where this ID is set.
Thanks for the tip. I will follow the steps and will post the results.
Unfortunately, I found the "restricted_to" field empty for all items. Any other ideas? I would appreciate any guidelines ...
You might also have other type of restriction stored in table restriction_to_roles.
Check what roles ID this user was related to his account and compare with role_id present in this table
Following the suggestion, I checked the table restriction to roles, but it was empty.
Luckily, I retrieved the items in another way: I wondered what the table "cache" is, so I searched through it and found some historical data. Realizing it might contain what I do need, I ran a simple query
SELECT * FROM `teampass_cache` WHERE author LIKE '<user ID number>' and folder LIKE '<folder name>'
and was able to see the hidden details.
I hope this can help someone else.
Thank you for your time and efforts.
Customer support service by UserEcho