improve editing of hashed email in admin

bam/admin.py

@@ -7,14 +7,22 @@ from .models import Account
 
 
 class AccountInlineForm(forms.ModelForm):
-    hashed_email_set = forms.EmailField(label='Set hashed email address')
+    hashed_email_set = forms.EmailField(label='Set hashed email address',
+                                        required=False)
+    hashed_email_clear = forms.BooleanField(label='Clear hashed email address',
+                                            required=False)
 
     class Meta:
         model = Account
         fields = ['hashed_email']
 
     def save(self, commit):
-        self.instance.set_hashed_email(self.cleaned_data['hashed_email_set'])
+        if len(self.cleaned_data['hashed_email_set']) > 0:
+            self.instance.set_hashed_email(
+                self.cleaned_data['hashed_email_set']
+            )
+        elif self.cleaned_data['hashed_email_clear']:
+            self.instance.hashed_email = ''
         return super().save(commit)