You can clear the expired data or all data of an ApsaraDB for Memcache instance in the console.
Procedure
Log on to the ApsaraDB for Memcache console.
On the Instances page, click the ID of the required instance.
On the Instance Information page, click Clear Data in the upper-right corner.
In the dialog box that appears, select All Data or Expired Data.

All Data: Clear all data of the instance.
Expired Data: Clear the expired data of the instance.
WarningData clearing takes effect immediately and cleared data cannot be restored. This may affect your business. Proceed with caution.
Click OK.