I want to open just a drain cleaning business(NO PLUMBING REPAIRS AT ALL) Just drain cleaning. I want to know if I need a plumbing lic. Or a contractor lic. To do this in Miami Florida. Thank you for all the help!

Check with the Miami Dept of buildings or consumer affairs. They can answer you. Such licensing requirements is generally on the City or County level

Services that require a license - Construction Contractors

Not on list so you have to call the number shown