Create a query to remove last two characters of a string

I am writing a Sql query where I need to remove the last two characters of a string. The string length is variable (6 or 7).

The following query works for the 6 character string

SELECT SUBSTRING(Col1,-1,LENGTH (Colname) -2) AS COL_1, COL2 AS COL_2, COL3 AS COL_3
FROM lib.Table
LEFT JOIN Lib2.Table2 ON lib.Table.Field1=lib2.table2.Field2 AND lib.table.Field3=lib2.Table2.Field3

WHERE Field1=180 AND Field4='A' AND COL3 <> '' AND Field5 = 'Field_5' AND Col1<999999;
ORDER BY COL1;                                                                                                                                                                      The following works for the 7 character string

SELECT SUBSTRING(Col1,0,LENGTH (Colname) -2) AS COL_1, COL2 AS COL_2, COL3 AS COL_3
FROM lib.Table
LEFT JOIN Lib2.Table2 ON lib.Table.Field1=lib2.table2.Field2 AND lib.table.Field3=lib2.Table2.Field3

WHERE Field1=180 AND Field4='A' AND COL3 <> '' AND Field5 = 'Field_5' AND Col1<999999;
ORDER BY COL1;

How can I write this so it works for both string length or how do I link these two queries together?

For the seven character string records, the last three characters are removed, instead of 2 when I use the first query.

I'm a newbie, I hope this makes sense. Thank you