If you cancel your subscription, in your free trial, your account will be suspended immediately and you will lose all access to all features on the app including sending a signature request. 
If you cancel your subscription for a paid account i.e. during your billing cycle, you will be able to enjoy your current plan with all the features until the end of the billing cycle, after which your account will be suspended.
When your account is suspended you will have three options:
1. Reactivate your account in the same plan 
2. Reactivate your account but with a different plan 
3. Switch to a basic free plan.
You can do this by:
1. As the account admin, go to admin management page on the side menu
2. Select Plan & billing 
3. Click on Change plan or Reactivate
4. Select your desired plan 
5. Select your number of licenses
6. Click on Pay now.