DBCC SHRINKFILE on the distribution database
It is ok to shink the datafile,  there WON'T be any data loss. 

The "issues" when shrinking could be performance, during the rellocation of data pages. Also if you know that your DF will grow again to the same size, shrink is not recommended. If it was because a one time only operation, or other stuff where the DF won't grow at the same big size again, it is ok to perform your shrink operation.