United are six points adrift of safety at the bottom of Sky Bet League Two and were knocked out of the FA Cup on Friday night after losing 2-1 at home to Vanarama North side Blyth Spartans.
Former Pools midfielder Murray only took over from Colin Cooper as manager in October.
But the 38-year-old has struggled to improve the club's fortunes and has lost his job after just 45 days and seven matches in charge at Victoria Park, during which Murray presided over five defeats, one win and a draw during his brief tenure.
"Hartlepool United can announce that Manager Paul Murray and Assistant Manager Willie Donachie have been released from their contracts," read a statement on the club's official website.
"Sam Collins has been placed in temporary charge of First Team affairs.
"The Club will be making no further comment at this time."