How do I clean my desk top?

Here are a few options that might work for you:

https://homeguides.sfgate.com/clean-oily-residue-wood-furniture-97881.html

Try using Murphy's Oil Soap to clean the grime. Then Old English lemon oil.

You can clean it well, lightly sand or use a deglosser and apply two coats of clear varnish or varathane to bring back the shine.

All you need is KrudKutter which you can find st Walmart, Lowe’s or Home Depot. Spray it on the areas and let it sit for about 30 seconds then wipe it off. This stuff will Not damage wood or any other surface. I use it to clean the same areas on my desk. KrudKutter is an amazing cleaner. It’s also great for cleaning kitchen cabinets but is safe enough to use on laundry.

Milsek wood cleaner. Easy to use and makes a big difference.

Add 1 cup ammonia, 1/2 cup vinegar & 1/4 cup baking soda to 1 gal hot water. Mix well & wipe desk with a rag. No rinsing necessary. Can also be put in a spray bottle.