How do I uninstall fonts in version 188.8.131.52?
You don’t uninstall fonts in LO, you do that in the OS. LO displays all fonts provided by the system.
Since you didn’t mention your OS, no better advice than read your OS help can be given.
In case you want to explain why you try to “unisnstall” from from LO, edit your question (don’t use &Add Answer" which is reserved for solutions). I feel you’d like to see a shorter list with only the faces you intend to use. This is not possible (the menu always shows what is available in the OS). The correct way is to design or customize styles (paragraph and character ones) so that you no longer need to use the font menu.
To show the community your question has been answered, click the ✓ next to the correct answer, and “upvote” by clicking on the ^ arrow of any helpful answers. These are the mechanisms for communicating the quality of the Q&A on this site. Thanks!
In case you need clarification, edit your question (not an answer which is reserved for solutions) or comment the relevant answer.