How do I clear finished hikes out of my Planned Hikes list?

Mark them complete rather than deleting them: open the hike, tap the checkmark at the top of its page, choose the day you finished and tap Mark as completed. The hike moves to your Completed list (Home > My Hike Lists > Completed) and is hidden from My Planned Hikes.

A hike overview with the checkmark at the top highlighted — Tap the checkmark

The When did you complete this hike? calendar with the Mark as completed button highlighted — Tap the checkmark

The Hide completed chip at the top of your planned hikes only hides hikes you’ve marked complete this way — tap it to show them again. In the Completed list you can search and filter your completed hikes like any other hike list.

My Planned Hikes with the Hide completed filter highlighted — Hide completed