[sorting] fixing cleanup

oephys2nix/sorting.py

@@ -36,6 +36,7 @@ class AppendSorting:
             self.sorting, mode="extremum", peak_sign="neg", outputs="index"
         )
         self.data = self.block.data_arrays["data"]
+        self._clean()
         self.append_sorting_to_recording()
 
     def append_sorting_to_recording(self):
@@ -82,12 +83,14 @@ class AppendSorting:
     def _clean(self):
         try:
             gr = self.block.groups["units"]
-        except:
+        except IndexError:
             return
 
         for das in gr.data_arrays:
             del self.das[das.name]
-        # for mtag in gr.
+        for mtag in gr.multi_tags:
+            del self.block.mulit_tags[mtag.name]
+            del self.das[mtag.name + "-positions"]
 
     def close(self):
         self.nixfile.close()