I found a formula from @Bassam Khalil that had me create helper Columns for AM/PM, Hours, Minutes.
The first three formula's appeared to "work" but when I used the forth formula for helper column 24H it was #UNPARSEABLE (Formula used below). I changed "Time on Site" to my Column name.
=IFERROR(LEFT([Time On-Site]@row, 10) + " " + IF([AM PM]@row = "AM", Hours@row + ":" + Minute@row, VALUE(Hours@row) + 12 + ":" + Minute@row), "")
Not sure what I am doing wrong. If there is an easier way please let me know!