Thank you, Bernie, your first link solved my problem in putting the OC in maintenance mode. However, your second link is the same exact one in my original question. That is the one that I can not follow probably because it is too technical for me and also there are lots of mismatches between the OC versions.
Here I copy paste the part that I try to imitiate:
Manually disable locking state:
1.put ownCloud in maintenance mode: edit config/config.php and change this line:
'maintenance' => true,
2.Empty table oc_file_locks: Use tools such as phpmyadmin or connect directly to your database and run:
DELETE FROM oc_file_locks WHERE 1
3.disable maintenance mode (undo first step).
My problem is number 2 now. I do not have/know phpmyadmin. How to run that command from my database?