If it's like my TS
- get M/B in exposed and supported area: slide out its M/B tray so you can approach clip from the side which covers the slot-A's release lever (nearest KT7's edge)
- put medium flat-head screw-driver into top hole on clip, just above clip's latch (top hole has inside pocket to keep screw-driver in place)
- stabilizing (pressing) fan / cooler with one hand, push the clip down and pull it outwards from the socket in one motion of the screw-driver -- yeah, this only makes sense after you've done it! 🙂
Wish I weren't so familiar with this operation: after 3 tries, penciling the L1 still hasn't worked; this weekend I'll do it once more using the defroster-repair paint from an auto-parts store rather than a pencil.
I wouldn't push down on the polished top of the clip: too much chance my screw-driver would slip off, crash into the M/B and risk damage. A screw-driver won't slip out of the top hole in the clip, so that seems safer to me. Subversal's probably a lot less clumsy than I! 🙂