Need help for SQL syntax for modifying table content

Hi, I have an issue with application "Roundcube" and this could be fixed by this: "Remove from the roundcube DB users.preferences the 2fa configuration."

The relevant table entry is this:

MariaDB [roundcube]> select preferences from users where username='<username>';
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| preferences                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| a:7:{s:10:"trash_mbox";s:5:"Trash";s:11:"drafts_mbox";s:6:"Drafts";s:9:"sent_mbox";s:8:"Gesendet";s:9:"archive_mbox";s:7:"Archive";s:24:"twofactor_gauthenticator";a:3:{s:6:"activate";b:1;s:14:;}}} |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

Can you please advise how to the table? What is the correct syntax to use?

THX