Unable to delete/remove Custom Fields

Hi,
I did try out the Custom Fields in the “”edit page window”, just to see what could be put in there.

One custom field has the name ocs_keyword and the value of iRobot,560,Roomba,Vacuuming,Robot,Auto Virtual Walls,free shipping.

The second Custom field has the name posts_rate_key
with the same value as the first one.

If you have a look at my page (https://roboticvacuumcleanercomparison.com/560-2/)you can see those keywords repeated several time near the bottom of the page.

There is no way I can get rid of the Custom Fields, when I press the Delete buttons
they disappear, but come back again after I update the page.