First, you'll want to visit the plan tab of your Admin Panel (gear icon in the upper right-hand corner of the page) to confirm what user tier you are currently enrolled in:
If you'd like to schedule your plan to renew at a lower tier than your current one, you'll first want to archive/delete users to fall into that tier (See: Archiving/Deleting A User on a Business & Enterprise plans)
Once you've done so, you can select the desired tier for renewal from the Plan tab of the Admin Panel:
You'll receive a pop-up asking you to confirm this scheduled downgrade. Click "Schedule Change" to confirm:
You'll see that your Current Plan information will update with the scheduled change and that you can cancel the change at any time by clicking the green text:
Note: If you schedule your plan to renew at a lower user tier than you are currently enrolled in, but your user count increases past that tier's allotted users before renewal, you will renew at the higher tier instead, and we'll send you an email notification explaining that your subscription could not be renewed at the scheduled tier due to a user count that exceeds that tier.