If Wes Jenson attacks and the attack misses, can Wes then remove the Evade token that Laetin gains from the attack not hitting?

Both have the same timing trigger so the order in which they happen will be decided by initiative - the player with initiative will have their ability trigger first

Therefore if Wes has initiative he won't be able to take Laetin's token as it will be assigned after Wes' ability tiggers.

see FAQ page 4 and Rules Ref page 8 and 12