Dell Inspiron 17 (5749, Early 2015) - Manual (Page 71)

Procedure
1 Turn the system-board assembly over and place it on a flat and clean
surface.
2 In sequential order (indicated on the heat sink), loosen the captive screws
that secure the heat-sink assembly to the system board.
NOTE: The appearance of the heat sink and the number of screws
will vary depending on the configuration you ordered.
3 Disconnect the fan cable from the system board.
4 Lift the heat-sink assembly off the system board.
1 fan cable 2 captive screws (3)
3 system board 4 heat-sink assembly
71