convert motor 2-prong plug to 3 prong plug

Hello DIYers, So, I've replaced traditional wired door bell by a nice tiny wireless (Bluetooth) doorbell. It works GREAT. Now I want to completely get rid of old door bell system permanently. How can I get rid of the doorbell transformer (located in my basement ceiling) safely? I suppose it has 1 AC wire incoming and 2 wires outgoing - one to the bell chime and the other one to the doorbell button outside. Should I just disconnect 2 outgoing low-voltage wires, remove the transformer and leave the AC wire as is? Any way to deactivate that AC wire? I'm not sure and I want to do it safely and appropriately. Also once that's done, can I just pull off the 2 wires? I want to fill the tiny hole caused by the door bell button and before I do that I want to take the wires out completely altogether. Can/Should I do that? Please advice. Looking for your response. Thank you.

This morning I found a puddle under my breaker box. The pipe that carries the wires from the electric meter on the outside of the house to the inside of the house (back of the breaker box) appears to be the source. After digging down to investigate it looks like the pipe may have corroded away. See the pictures attached in the link https://imgur.com/a/FH7fVrA What should I do to stop the leaking?