How to properly clean a bundt mold without ruining the surface

I hope you're using cake release! And you've never actually "seasoned" it (as in covering it with oil and baking it in a very hot oven). If you did season it, that's a problem. I'll get to that in just a second.

Otherwise, all you need is to wash the pan right away in hot soapy water (use a high-quality dish soap, ultra-cheap ones don't work as well) after each use. If necessary, soak it for a half-hour or so in hot soapy water (as in for hand washing, not machine-dishwashing detergent). Then wash it with a dishcloth. If you still have stuff stuck in crannies, use a soft toothbrush. Dry thoroughly. That's it. If you still have stuff stuck on, use a plastic scrubby sponge-like this (my favorite), or this.

Do you absolutely know what surface it is? Unless it says otherwise, don't season it. If it is made by Nordic Ware, look for any model number or anything it says on the box about seasoning or not seasoning. If this is your pan, don't season it. I've got their number. I'll call them if you still have questions, and if this is, in fact, your pan. If you seasoned it, please don't do anything else until we contact the manufacturers. Just catch me in chat, you know I'm almost always there.

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There is an answer somewhere on this site (Seasoned Advice) that says that Nordic Ware tells you to season their pans. Please note that that answer refers to pans that DO NOT have a non-stick coating.