[Help] Sink Holding Standing Water, Can't Remove Drain Stop - What Should I Try Before Calling My Plumber?

Hi all,

I’m hoping to get some help from any handy people or plumbers here. My sink is holding standing water, and while I was able to plunge most of it out earlier today, the issue seems to persist. The problem appears to be behind the drain plug, which I can’t seem to remove. It fits snugly and I’m not sure how to get it out.

When I plunged earlier, some black gunk came out, which I suspect might be grease or something similar. I also tried pouring boiling, soapy water down, but that didn’t seem to help.

Here’s what I’m wondering:

How do I remove the drain plug? It’s firmly stuck, and I don’t want to break it. Any tips or tricks to get it out would be appreciated. What steps should I take next before calling my plumber? I’m considering trying the baking soda and vinegar method, but I don’t have any baking soda on hand. Is it worth running to the store for it, or is there another method I should try first? I’m asking this before calling my plumber in hopes of saving him a trip and some time.

Thanks to anyone who can offer helpful advice. I appreciate it!