I work at a store with a parking lot that has towing enforced. Can I tow someone’s car legally without getting in trouble?

As the title says I work at a shop in Houston where their signs all over the parking lot that says towing enforced well lately a lot of stores in our company have been getting robbed so we have one assigned parking spot in front of our shop for our customers and that's where our cameras are pointed.

Every now and again we'll get a dick head that doesn't know how to read signs and they will park in front of our shop and go leave to go gambling or something else so their car sits there for hours on end.

Basically it boils down to a security issue because our cameras are pointed directly at the spots for our customers, every single time we've been robbed the people robbing us park in that front spot because it's a quick getaway. Now I've got a dick head that parked in my spot and left. The other passenger went to the gambling spot on the corner and they don't let you in without a password, even when I told them that I don't want to go in and I just want to tell this person before I tell their car, they just ignored me.

Finally I just called the tow truck company and they have a new policy where the landlord is the only person allowed to tow cars, so they told me I needed to have him call and get the car towed.

I called the landlord and he didn't want to do it because he was worried he might get sued by the people that got their car towed. I tried to tell him that we have signs posted everywhere that says do not park in these particular spots and people do it anyway. He said he understands that I'm worried about getting robbed and that his hands were tied and he couldn't do anything.

I tried googling this thing because I'm 99% sure he's not going to get sued, and even if he did, he would win anyway because their signs everywhere. Is there like a particular law or something about towing and whatnot? Could he even get in trouble like he thinks he will? For all I know he's just being a lazy dick and doesn't want to lift a finger to do anything about it, I don't know…