update sql row with time 1 hour before NOW()

hi i am having trouble updating a sql row

i want to set it so it updates row lastmergedate 1 hour before now

UPDATE `Table` SET `lastmergedate` = NOW() works for setting the time as now

but e.g UPDATE `Table` SET `lastmergedate` <= NOW() 1 interval hour does not work

any help would be much appreciated

tried

UPDATE `Table` SET `lastmergedate` <= NOW() 1 interval hour

but get mariadb errors