Hello, 

Well I wouldn't recommend to remove the temporary folder no. But yes you can delete its content.

Hello ,

the content stored in this folders are indices generated for elastic search,

If you are not using search functionality or if you are using any other means it is good to delete the contents.

Or else you can limit your search functionality to Work or data or rule instances in Search landing page

Configure->systems->settings->search

It is a practice we are following in our PROD env, Disabling the Search for Work, Data and Rules. If you are not using the search, yes , it is Safe to Delete the contents of the Search Folder. But do not delete the folder. 

We often restart the JVMs if we do any operations with temp directory [which includes search as well].

Check if you have work indexing enabled.  If so, your search index will increase in size relative to the total number of cases in the system.

Deleting it would make search inaccessible and could take a long time to rebuild the index.