How to remove DVR'd shows that I don't want to watch?
That's a function of whatever channel/app you're using. The Roku device itself has no DVR capability. If you tell us what channel/app you're using someone may know or you can try to get support from the developer of the channel/app.
This question is better asked here:
https://community.roku.com/t5/Channel-Issues-Questions/bd-p/channel-issues