Question about vintage clocks that plug into wall  

Yes
I have some that have the cord coming out the bottom of the center base of the clock, and have with some removed them to go through a hole in the back and into a wall where the plug and wire runs down through the wall to another outlet.
When doing so, disconnect the wires from the clock, run the wire and then reattach the connections.
If you are going to have it non-operational and purely for design, be sure to keep the wire somewhere safe as it's loss will affect the sale price/value.
And take your time.

Thanks!
Thank you. I just bought the clock, on ebay, but then realized you were referring to clocks with electrical cords. This one just has the plug only. I think it was meant to plug directly into a wall outlet. Hopefully, I can still remove the plug and hang it for decoration.

just a screw
If it is a Howard Miller clock, I'm pretty sure the external plug is just attached with one screw. When you remove the screw, the plug comes off and exposes the electric power wires for the clock. I would recommend removing the back plate of the clock and re-wireing it directly to the motor however.