Hendry took over the Seasiders in June 2004, weeks after he had been in line to takeover at Scunthorpe before a boardroom coup saw Brian Laws reinstated as Iron boss.
A Blackpool statement said: "Following discussions with Colin Hendry on Thursday, Simon Grayson has taken temporary charge of first-team matters.
"Messrs Colin Hendry and (assistant) Ian Miller, in line with their request, are scheduled to attend a further meeting at the end of next week to discuss the club's position.''
Blackpool are fourth from bottom of League One going into this weekend's fixtures.