What do I do if I just signed up for an investment with a company or advisor that I no longer feel comfortable with?

Talk to the company directly to see if they are flexible and will consider your request.
If not and you have already signed up in the last 24 hours, call the ASC and you might be able to get out of the investment under something called the rights of recision where you have a 48-hour period to get a full refund. See section 209 and 210 in the Securities Act (Alberta).
If 48 hours have passed since you signed, you will need to talk to a lawyer to determine what actions you might be able to take.