how do i lock topics

someone just lock it how do i unlock it and locked it

It's only for the admins and moderators of the site.

Ya, people with the user title "Moderator" or "Administrator" are the only ones who can lock/unlock topics.Topics are usually locked if they violate forum rules. Which you can find here:
https://www.romulation.org/forum/index.php?topic=4312.0Or if they are duplicate threads of existing active topics, in which case discussion should be kept to that existing topic. Also if a thread is posted in a wrong section, it will be moved to the correct section, and the old thread in the original section will be locked.