If i delete a form from my account, will it stop working on the website it is on? Or do i have to purge it from jotform to do this?

Website was made with dreamweaver then uploaded . 

If you delete, Form will not work on site.

That is half correct but only if the form has been Deleted and Purged from your account completely. The reason being is that the Dreamweaver Embed option uses a similar format to the source code of the form itself so it is self-contained and runs entirely on its own even if it has been deleted but not purged.

DreamWeaver Embed Option:

Here is a test of the DreamWeaver Embed Code while the form was in the trashcan and not purged.

You can see this in my test screenshots below for proof of current fact:

I was able to receive a submission even with it in the trashcan but not purged.