Patient records cannot be deleted in Sensei Cloud. Instead, you must set the account to Inactive and can select to enter a ZZZ prefix to the patient's last name; for example, if the last name is Jones, rename it to ZZZJones which will then sort them to the bottom of the index of patients.
The Patient Record can be made inactive by accessing the patient's record and selecting Edit Patient Record. Change the Status from Active to Inactive; then click Save Patient.
In the future, the record will be hidden from the patient searches, unless you select to Display Inactive Patients.