@the.christopoulos yes, and @Nazarius was correct you have to do it by adding a datacolumn, iterating through it and converting from oldColumn to newColumn, then delete oldColumn and rename newColumn to the oldColumn’s name (last part is optional).
Here is some pseudo code to do it, i can put in .xaml if it isn’t clear:
Read CSV activity --> save as dt1
Add Data Column activity --> TypeArgument = Double (or whatever number type you want); DataTable = dt1; ColumnName = tempColumn
For each row in dt1 activity
Assign row.item("tempColumn") = CDouble(row.item("OldColumn")
Remove data column activity --> ColumnName = "OldColumn"; DataTable = dt1
Assign dt1.Columns("tempColumn").ColumnName = "OldColumn"
Replace “OldColumn” with the actual column name you want to replace. If you want to get extra fancy, you can also put the replaced column at the old spot by getting the .Ordinal property of the “OldColumn”, then setting the “tempColumn” to be at that Ordinal after deleting “OldColumn”