Community colleges often hire teachers solely based on applicable experience. For K-12, teaching without a degree may be possible depending on the demand and where you live.

I’m sure it varies from country to country, but here in Canada, at least Ontario, which is the only province that I am familiar with when it comes to teaching requirements, you would definitely need to attend teacher’s college, which is a two year program.

I used to teach CS to middle schoolers at a private school. Illinois doesn't require a bachelor's for teachers at private schools as long as the teacher has "demonstrated competence". I taught there part-time for twelve years and then full time for a year.

I taught computer classes for multiple for-profit schools without a degree. Not sure it was worth it though. ¯⁠\⁠_⁠(⁠ツ⁠)⁠_⁠/⁠¯

Many states have accelerated certification programs for K-12 education, and while some subjects would require a specific degree for secondary grades, many wouldn't. Then there's guest lecturing, adjunct work, and sketchy for-profit places will bring on anybody who knows more than the students.

So, I guess it depends on who you want to teach, how often, and in what context.

I got asked if I wanted to teach for teachers after studying half a year at university. It is an advantage, often a formal requirement, but in praxis not necessary to have a degree in order to teach classes. Personal qualifications on the other hand is a must.

I have a degree in CS with a minor in Earth and Environmental Science. I taught middle school science, and could have taught math.

I hope your want is for something other than English.

Yes. In the US, there are credential programs depending on what state you live in. At least for K-12.