How can I clean out a smelly shower drain?

Remove cover, clean out any hair blocking. 1/2 cup baking soda and vinegar, cover. Boil water and pour down after 10 minutes.

This link has a few tips for you:

https://www.realsimple.com/home-organizing/cleaning/cleaning-bathroom/how-to-clean-shower-drain

1 cup of baking soda+1 cup of white vinegar. Mix together quickly and pour down the drain. It will remove any clogs, and any smells;)

I would try baking soda and I wrote a post about unclogging drains. In it it shows what to put down a drain and this might help with the odors too - https://chascrazycreations.com/unclog-drains-toilets-with-out-plunging/

Try using white vinegar to help with the smell.

I use vinegar and then I stop up the tub so no water can get down and rinse it away for a bit. Works like charm.

Here are 8 quick ways to get rid of the smell: https://www.tipsbulletin.com/shower-drain-smells/

Scrub it with Steel Wool. Pour some Drano down when you are done.

Dump a good handful of baking soda into the drain, let sit (don't run any water) for 15 minutes, then pour 1/4 to 1/2 cup white vinegar down. Watch the bubbles, hear the pops and fizz, and let it sit for another 15 minutes. Then, boiling water and voila! It will be right as rain … at least for about six weeks.