Try this:
1. 'Launch Excel' with your file
2. 'Focus windows', class = XLMAIN
3. 'Select cells in excel worksheet': select column 4, row 1
4. 'For 1 to x' (you have to adjust x here... to delete final column CH, x=42)
5. 'Send keys' {LControlKey}({Space}) (Ctrl+Space to select all column)
6. 'Send keys' {LControlKey}({OemMinus}) (Ctrl -, to delete column)
7. 'Send keys' {Right} (to move 1 column to the right)
8. End of loop
Recording desktop will help find the correct keys in steps 5 to 7.
Also, you can put all 'Send keys' together (i separated them just for explaining purposes)