Here are some ways to clean inside your oven https://www.hometalk.com/search/posts?filter=clean%20oven
This is a good non toxic (no fumes) way to clean the inside of your oven: https://www.thekitchn.com/how-to-clean-an-oven-cleaning-lessons-from-the-kitchn-201191
The easiest way I've found is using a steam cleaner. Here is the one I use-affiliate link https://www.amazon.com/Homeright-C900053-M-SteamMachine-Model-Blue/dp/B01KVBG6AK/ref=as_li_ss_tl?crid=1X08D4Q1PTVWA&keywords=homeright+steam+cleaner&qid=1572367534&sprefix=homeright+ste,aps,151&sr=8-4&linkCode=ll1&tag=lydioutloudco-20&linkId=6e9dd7adaac3da99379fb031eaf87621&language=en_US
Spray inside of your oven with white vinegar & lemon juice. Sprinkle baking soda on top. Let side overnight and wipe out the next day.