Is it safe to clear buffer cache in Linux?

This is not recommended to clear the memory cache on Linux systems, but it is safe. But clearing cache may cause performance issues with the system. Since it discards cached objects from memory, it may cost a significant amount of I/O and CPU to recreate the dropped objects.

How do I clear the cache in Ubuntu?

Switch over to the Files tab, where you can change the option to “Delete downloaded packages after installation”, which will prevent the caching entirely. You’ll also notice that you can use the Delete Cached Package Files button from this screen to clean up the packages.