One thing to remember is that the clips have different 'depths' depending on how many layers of plastic they are designed to retain. So, buy an assortment, and take note of which holes you removed them from.
I've never used a specific tool to release the clips. I use two small screwdrivers on opposite sides to pry them loose. When the center 'button' is extended about 1/8" (3mm), the entire fastener should then be withdrawn. That way, you won't break them.
(But, don't forget that corollary of Murphy's Law: If you have spare clips on hand, you won't need any...SO BUY SOME, LOL) :applause: