Do I need to know grammar to teach English?
Some, but it’s not as bad as you might think. Many people immediately think ‘I’m terrible at grammar’ and this puts them off. If that’s you, don’t worry. It’s not the same as the grammar you’re remembering in school.
Yes, you’ll need to know what some word classes are (e.g. is this a noun or a verb) and you’ll have to learn some pedagogical grammar and technical terms too. However, note that if you’re a native English speaker, or a high level advanced English speaker, you know how to use grammar correctly already! So it’s really just a case of understanding why something is right, even if you ‘know’ it’s right already.
What’s more, grammar is only one aspect of teaching English. There are skills such as pronunciation, vocabulary, listening, speaking, reading, and writing. So if you’re scared that you’ll spend your whole time explaining the present perfect from the present continuous, you won’t (much).