I need help!! I'm slowly learning the Winbox, then i accessed remotely the device, but physically is with damaged label, then where find the MAC Address from this device?? Any command to find the physical MAC Address?

Can you see that mac in Winbox -> Neighbors -> Refresh ???
Also Wireshark should helps

Can you see that mac in Winbox -> Neighbors -> Refresh ???
Also Wireshark should helps

Neighbors only works when is connected to my machine / router. The device with damaged label is in the tower and can't be removed. I can access the device remotely only via Winbox / browser. Wireshark don't work here. Any idea?

If you can get in, then "/interface print" will show current MAC addresses and if they were changed, "/interface ethernet print detail" will also show original ones.

Neighbors only works when is connected to my machine / router.

Nope. It works if you have L2 connection, no matter how far you are. Same for mac telnet. If your traceroute shows 0 hops between your pc and device - it is L2 connection. if you have access to every single device between you and router - you can create your own vlan or EoIP/VPLS tunnel and get L2 connection between your PC and your router.

PS: if you have Winbox access why you need something else?