I want to thank Frank for his efforts over the last four-and-a-half years and wish him, his wife Wendy and the rest of the family all the very best for the future," Albion chairman Jeremy Peace told the club's official website.
"Following his appointment as our new manager, Bryan offered Frank a position on his coaching staff but he has decided to take a break and look for a new challenge elsewhere.
"We're sorry Frank has reached this decision but he has made his mind up and we won't stand in his way."