To change course in the same college contact the concerned department
To change college, apply to a different college - Wouldn't recommend doing this unless the course you are really interested in is not offered in your current college
There's no restriction on changing DLI. I have a classmate who enrolled in PG Diploma after his B.Tech and is currently
enrolled in an undergrad diploma with me. As an international student after landing you can change to any course at
whatever level (the only restriction is that your visa shouldn't be bound to your institute. This usually happens in
case of scholarship/bursary cases or maybe some other situation I am not aware of).
For the purpose of making it hassle free, CIC has in MyCIC a/c login given option of : Transfer DLI. So once you withdraw
from a program within 90 days you need to be enrolled in another full-time course and you must update this information
on MyCIC account or inform CIC by calling them.