Full deletion of Mac partition

I’m a college student with not a lot of money so I decided to try adding windows to my Mac that I’ve had for a couple years, along the way of trying to adjust the size of my boot camp partition so it’d have more space I deleted the entire Mac partition. When attempting to restart and switch to Mac it’s not even an option, only windows shows up, I’ve attempted the restart while pressing command - R, as well as the other to restart methods. I really don’t know what to do and I can’t afford to just up and buy a new laptop, any help would be awesome, I’m just tryna get Mac back into my laptop, a full wipe or reinstallation (idk what it’s called). I don’t care if I have to restart with a whole new system where I have to re-setup it all. I’ve seen another question on this but the person in question ran windows 8, while I’m stuck on windows 10 (but a crappier version). Please keep in mind that I’m not very tech oriented, hence this issue, so please be as detailed as you can be.