No point removing the rubber trim up the pillars if you want to gain access to the rubber tube. But as said get some spare clips first I usually break about 3-4 when I remove the trim. You're best off starting at the rear, then work your way forwards. Once it unclips off the back clip, pull the bottom of the rubber down & outwards to free it off the 'lip' along the roof, then it should unclip easily. Go steady though, and be careful you don't bend it as it is virtually impossible to straighten it again

Ideally you want to practice on a car in a scrappy first, and you can then nick some spare clips off it
