CB fields data storage Database structure differences: twitter facebook fields

I've disinstalled the CB FB and Tw connect plugins. I do Check CB fields data storage database and I go this error message:

CB fields data storage Database structure differences:
Table #__comprofiler Column fb_userid type is varchar(50) instead of varchar(255)
Table #__comprofiler Column twitter_userid type is varchar(50) instead of varchar(255)

The CB fields data storage database structure differences can be fixed (adjusted) by clicking here: Click here to Fix (adjust) all CB fields data storage database differences listed above (you can also Click here to preview fixing (adjusting) queries in a dry-run), but in all cases you need to backup database first as this adjustment is changing the database structure to match the needed structure for the installed version.

What should I do?

Also, how can I clean those plugins from DB? Just delete rows in the #_comprofiler_fields table or should I remove elsewhere?

If you don't have CB Connect, CB Facebook Connect, or CB Twitter Connect installed and want to remove their columns then navigate to CB > Field Management and delete their fields. If it won't allow you then you'll need to remove manually their columns from _comprofiler and their field entries from _comprofiler_fields.