I just measured my chain stretch for the first time and it exceeded my tools max measurement. So I bought a new SRAM PC830 chain and upon opening the box, discovered the sticky nature of factory grease. Which would be catastrophic for my dusty desert commute! So obviously, that has to come off. I consulted the web and found a brilliant website with charts for various chain lubes. https://zerofrictioncycling.com.au/
I ended up following KMC’s advice and cleaning the grease off with a light oil (WD-40 was handy). Then a wet lube (I forget the brand; whatever my LBS stocks).
Chain wear sticks have two measurements normally - if you are beyond the longer one, you may find that your rear cassette is worn too and that your new chain skips. Hopefully you’re fine though.
I have an old tupperware that I put degreaser in, stick the cassette and chain in there, wash, rinse, put on bike, then oil.