Recall that in many plants, if the shoot apical meristem is removed, axillary buds become active and new lateral branches form. what is this an example of?

This is the phenomenon of reverse of apical dominance ...

In apical dominance the root apex inhibit the growth if lateral buds ... in actual the terminal bud produce auxin that inhibit the growth if lateral buds ... if the tip is cut the influence of apex on lateral bud will lost nd they will emarge nd form branches.

Not only auxin is responsible for apical dominance but other hormone like cytokinin, gibberellins are also ...

But application of absicisic acid make the branches free of apical dominance ...