How to delete boot camp from my Mac?

So, not knowing what to do and didn’t think to take the proper steps to delete the bootcamp, I deleted it, by selecting it somewhere (it’s been a while and it hasn’t bothered me till now) and deleting it and throwing it away. so, how do I go about deleting the bootcamp all the way? Going into the bootcamp assistant gave me nothing and told me “The startup disk cannot be partition or restored to a single partition” “the startup disk must be formatted as a single Mac OS Extended (Journaled) volume or already partitioned by Boot Camp Assistant for installing Windows” did I screw it up by just deleting it and throwing it away?