Well, you could report it to your supervisor. They'll have to report it to whomever his superiors are. They will likely tell him to stay clear of you and to not talk to you unless its absolutely necessary. Then you could also get an audio recording device, keep it in your pocket ready to hit record, and anytime he gets near, hit record just in case he continues his behaviour with you, so you have proof rather than your word against his. If he has been with the company for a long while, its going to be very tough convincing people that have learned to trust him without proof to back it up. While you can report him and should, multiple reports from the same person are not going to get him disciplined or terminated if you have no proof and no one else backing you up. Best case scenario, they put you on a different schedule to where you dont see him anymore, if that is possible. If you report him and you gather proof that he is continuing his behaviour, he will have no leg to stand on and his superiors will have absolutely no choice but to take disciplinary action.
Also, you multiple people to complain to that could be held responsible. Is your employer a contracted cleanign agency seperate from the business you clean at? And is the security guard contracted from a different company?
Which ever the case, if you're both contracted, you have 3 different parties to complain to, your employer, his employer, & the client you both work for.
If not, you still have 2, his employer and yours.
In either case all parties would want to steer clear of any potential legal ramifications and as such will make sure it does not continue to be a problem one way or another. But like I said, if you dont have proof, one way, may be that you are the one that gets moved to a new shift, or if you're contracted, you may simply get moved to different client. If he has no other complaints or reports against him and a client that trusts him and will back him up.. they're not going to allow a single report without proof send him packing.
Do both. Sounds like the guy might've been working there for a while. Also if he's on his own a lot. He can get away with a lot. People only really behave themselves if they're around supervisors or managers a lot when working. They're being observed, therefore their behaviour will be noted. Seen that in retail, but it's not great if the managers are douches too.
Report him. Make a complaint. If you have too. Go to his supervisor. I mean if he's security than there's likely camera's everywhere. His behaviour could be on a recording if the camera is in say the corridor leading to the woman's loo.
I've seen a guy in the woman's loo twice. First time he was changing out the sanitary bins. So it was his job. Poor bloke. The second was two guys, both plumbers trying to unblock a loo. Fun times.
This is something to talk to your human resources department about. Every time he does something like that, write it down, along with the time and date. Documentation is your friend here. He sounds like he's creating a hostile work environment and such behavior should not be tolerated.