Welcome to the community!
What you are looking to do is called a temporary suspension. You will need to contact customer service to have the line temporarily suspended.
A few things to note:
The suspension will be automatically be removed after the set amount of time you had it suspended for. If you would like to have the suspension removed earlier then you will need to contact customer service to have it removed.
Fido has many different ways to contact them you can find all the different ways here.