Post #4 of this link has a pic.
Put your two thumbs on the flat part of the clips and push up and out to release it.
Many people complain about them being a PITA to latch; mine is too, so once I have it open for the season, I've rarely closed it again.
1988 Coleman Sequoia - popup (1987-2007)
2012 Roo19 - hybid (2012-2015)
2016 Mini Lite 2503S - tt (2015 - ???)
2011 Traverse LT, 3.6L, FWD
2009 Silverado Ext Cab, 5.3L, 4x4, 3.73
2016 Silverado 2500HD Dbl Cab, 6.0L 4x4, 4.10