Can I manually delete rows from the database?

Dear staff,
I have installed your plugin, but spammers can still register at my site. The cause might be another plugin I use for registration, but this isn't my most urgent problem at the moment.
The point is that, having set the option "log to db", now the spambotcheck tables are taking more than 1GB in space.
This means that I have run out of database space and nobody can visit the site anymore, since Joomla! can't save their data in the session table.
This also means that I can't access the control panel to verify what options are or aren't set. I can only access to phpmyadmin to do maintenance.
Is it safe for me to run a query such as "delete * from __user_spambotcheck", so I can at least free some space from the database and have my site visible again? Or will anything stop working?
I have other questions, but if I don't free some space nothing else could help.
I hope you can help me,
SabrinaWeb

Hi,

the "log spambots to db" option logs all blocked spambot attempts in the table #__spambot_attempts.
I think it is this table that causes your troubles and not the #__user_spambotcheck.
The #__user_spambotcheck table contains only one record with only 5 fields for each registered user of your website. This is much less than for example the Joomla! core #__users table itself, so I think, this table would not be the problem.

You can remove all record sets from the #__spambot_attempts table manually, savely.
But do not remove record sets form the #__user_spambotcheck table because this table is "linked" to the #__users table. For each user in the users table there must be a record set in the #__user_spambotcheck table, too. So you have to delete users via administration, in order to make this tables (plural) smaller.

Regards,
Aicha