This was a topic that Sinclair covered in detail about 2-3 years ago. You may want to go to the JSMINESET website and do a search on stock shorting or taking possession of your shares.
Briefly, here are some subjects you may want to research on your own. Also this is from a US point of view and financial rules and regulations in the states are different from Canada.
1st) Eliminate all margin. As long as your account has access to margin any equity can be shorted. Eliminate the margin option from your account and the shorting goes away.
2nd) Take possession of your shares in paper physical form. They can't be shorted at all.
3rd) For retirement accounts in the US put your shares in safekeeping mode at your brokerage account. Many brokerages don't offer this service. Several do such as Schwab. There is a fee for this service but your shares can not be shorted.
4th) Become a book entry registered in the transfer agent for the company that you own.
I am not a financial advisor so do your own due diligence. Also most brokerage accounts that you deal with will be against these options because it takes away from their book of business and the multiple options associated with the standard way of doing business so do your homework and prepare for resistance from your brokers.
