can I remove the beep speaker from apc easy ups?

Just cover its hole with some sticker/duct tape, this can almost completely mute it.

Server (Ryzen + 3 HDDs + 2 SSDs) - 50W

Networking (USG + Unifi AP + Mi router as a second AP + switch) - 20W, maybe a bit less

70W in total

"rent my roof" for a new wireless start up in my area.

Looks suspicious already

​

they are installing an antenna on my roof and it will be hardwired to my router..

It smells not very good

​

.they have assured me that my personal network would be at no risk

If they are wired their access point (I suppose this "antenna" is one) to a LAN port of your router, I am suspecting you are exposing all your network to the wireless network this access point creates.

I am using it for media server, Ubiquiti controller, torrents, sync and local http server.

Simply because it is a nice and simple front-end for Docker.