Go to your Amazon account online, click on your ‘Accounts & Lists’, then ‘Manage Your Content and Devices’. In the upper left side of the screen you’ll see a rectangular box next to the word ‘Show’ that’s entitled ‘Books’, click on it & a drop down menu will present itself. You show now see a list of options, click on the one entitled ‘ Collections’.
From this screen you should now see all of your created Collections ? Notice the square box beside each of your collections (under the ‘Actions’ column), click on the box and you ought to be to able to edit the name or delete the collection.

Have a play around with various options for that ‘show’ box and you should be able to find those guides & delete them.