Sometimes I go away and come back and there 50-100 messages on my device that I have already taken care of on my desktop computer. I scroll through them with my finger on the shift key to select them all, then click delete. It works, but I want to know if there is an easier way to delete all the messages in the inbox?

go to the date and click and select delete prior. It deletes everything.

Change the Wireless Reconciliation to Desktop and Handheld. Keeps things in sync no matter where you delete from.