Can I cut or cover a sewer cleanout pipe in front of my house?
You will need PVC cement and primer, and a female pipe adapter (available at your local or big-box hardware store; measure your existing plug -- it looks like 4" in the photo).    Dig out around the pipe to get enough room to saw it off near ground level (any sharp hand saw will work).   De-burr the edge with a piece of course sandpaper or a file, and follow the instructions on the cement and primer to glue the adapter on.   Give it some time to set, replace the plug and backfill.   As @Scott mentions, measure where it is so that years from now when you need it, you will be able to find it.    If the sewer line runs through your basment, mark the location on or near where the pipe exists the house.