I need to replace the ignition switch but I can't get the bottom half of the shroud on the column off

See if this helps:

Ignition Switch Replacement

1. Disconnect negative battery cable.

2. Remove dashboard lower cover and knee bolster.

3. Disconnect 5-P connector from under dash fuse box and 7-P connector from main wiring harness.

4. Remove steering column covers.

5. Insert key and turn it to "0".

6. Remove two screws from switch and replace.