You can separate the values using the Split function (I'd also add trim as a second function to get rid of extra whitespace, but make sure it occurs after the split). With the Split function, you just tell it what character to use as the delimiter for the split, which in your case is the semicolon.

You can use the Split function in places where you utilize the token by right-clicking and opening the Token Editor (provided where you're using it can support multivalue).

In the first example below, I'm using it to split and store the values into a new multivalue token, but you could also use split with a For Each Value activity (last screenshot) if you need to iterate them.