Welcome to the community!
Only a Fido representative can apply a temporary suspension on the line, you will need to get in contact with customer service to have it done.
You can contact customer service through any of the available methods listed here.
A few things to note before you proceed with the temporary suspension.
I also want to hold on my account. Because I'm still in my country and I will come back to Canada by December 30th. I don't know how can I apply through this online. I will appreciate it if you respond to me by email.