The male suspect struck at the One Stop branch, in Cresswell Crescent, Mossley, in Bloxwich, on April 19 after arriving on a distinctive bicycle with the word 'venum' in yellow lettering at about 3.45pm.
Officers at Walsall Police investigating the incident said the man, whose head and face was covered with a hood, threatened staff with a metal pole before forcing them to hand over an undisclosed sum.
Now they have released an image of a man they want to identify in relation to the robber and have appealed for anyone with information to come forward.
"They were forced to hand over a large amount of cash. Thankfully no one was injured", West Midlands Police said.
The force said the man left the scene on the bike.
"We know you can’t see the suspect’s face, but we think he’s from the local area. Please get in touch if you think you know who it is," it added.
Witnesses with information should message the force via the website west-midlands.police.uk or phone 101 quoting crime number 20/313896/22.