Firstly, unscrew the lid, open the flip-lid and pull the straw stem out of the silicone straw top. Then pull on the tab to release the straw top. Easy!
To reassemble, push the silicone straw top into the lid and turn the lid over, then pull the straw through until you feel and hear it click into place.
Reconnect the straw stem to the silicone straw top ensuring the cap of the straw stem is pushed in and tightly covering the base of the straw top.
Screw the lid back on and you’re done.