How to Kick Inactive Members from Discord Server?

If nobody has recorded any action in the server for a specified period of time (less than 7 days or less than 30 days of inactivity), then pruning will kick them from the server. It will not ban them! Just for reference, 'any action' means anything recorded in the audit log or visible to other members in the server. This could be as minor as changing one’s nickname, reacting to a message, or joining a voice channel. 

Just like the arborist term, pruning means to cut back the growth of a server so that it has room for new growth in greater abundance. If your server ever stops growing, it’s never a bad idea to prune out long-inactive members. 

You may want to alert all members that you will be doing this before going through with it, just to be courteous. If you choose to alert them, give them a 7-day grace period to resume activity in the server.