When I worked in a shitty part of town we had a HUGE bum problem. Really just out of control.
They would go through our garbage looking for metal/copper, literally shit and piss in our parking lot, break beer bottles everywhere, and sleep under the overpass that went over our property.
There were about 20 of them all together and they'd roll in groups of 3-4.
Let me just say FUCK avoiding confrontation. If you don't want them on your property, grab a couple big cans of pepper spray.
Our policy at first was warn them a few times, try to walk them off the property, and if they didn't listen we'd call the cops. The spray was just a scare tactic. Then they started getting worse, started ignoring us and literally moved a couch into our parking lot.
As you can see - we didn't appreciate that at all - and quickly did away with the couch in a reasonable and mature manner.
After that, we would warn them to get off the property slightly before or during spraying them down with police grade pepper spray.
I personally sprayed one guy in the dick that was pissing (pants around his ankles) in the middle of our parking lot in full view of one of the busiest intersections in the area. Sprayed another guy in the face that was in our dumpster, and sprayed him again when he pulled a bowie knife on me when he could see again. Sprayed ANOTHER guy who wandered into our lot and took a swing at a doorman that was trying to get him off the property peacefully...
And we even had a couple stand-offs with the group of Nigerian refugees that would come sell drugs around our business. We knew one of them carried a gun but could never figure out which one, so when three of them were harassing the people at the bus stop and 5 of us walked out there with our (holstered) guns, it was a pretty intense moment while we waited for them to back down.
The only thing you can do with these people is be tough with them, unless they are looking for work, not hand-outs. We had another guy that we'd pay to pick up cig butts, sand down the tiles on the front entryway, do general repair work... even gave him some free beer on occasion because he wanted to WORK for the money we gave him.
The other guys/girls though, they will annoy the fuck-all out of you until you finally put your foot down. They're transients so it's not like they're going to give a shit if they go to jail for a few days. They'll be back bugging you again. And if they're on your property or you think they're going to harm you - pepper spray the fuck out of them. Check with your local PD first on the matter but when we talked to 2-3 different supervisors all of them said just spray them instead of calling.