Remove unused test function (#529)

Everything has already moved to `mantid.texting.assert_not_equal()`

tests/util/helpers.py

@@ -12,7 +12,6 @@
 from mantid.api import ITableWorkspace, MatrixWorkspace
 from mantid.dataobjects import GroupingWorkspace, MaskWorkspace
 from mantid.simpleapi import (
-    CompareWorkspaces,
     CreateEmptyTableWorkspace,
     CreateWorkspace,
     DeleteWorkspace,
@@ -211,29 +210,6 @@ def deleteWorkspaceNoThrow(wsName: str):
         pass
 
 
-def workspacesNotEqual(Workspace1: str, Workspace2: str, **other_options):
-    """
-    Meant to be called as
-    ``` python
-    assert workspacesNotEqual(ws1, ws2)
-    ```
-    Parameters:
-    - Workspace1: str -- one of the workspaces to compare
-    - Workspace2: str -- one of the workspaces to compare
-    - other_options: kwargs dict -- other options available to CompareWorkspaces
-    Returns: if the workspaces are NOT equal, will return True
-    If the workspaces ARE equal, will raise an assertion error
-    """
-    equal, _ = CompareWorkspaces(
-        Workspace1=Workspace1,
-        Workspace2=Workspace2,
-        **other_options,
-    )
-    if equal:
-        raise AssertionError(f"Workspaces {Workspace1} and {Workspace2} incorrectly evaluated as equal")
-    return not equal
-
-
 def nameOfRunningTestMethod(testCaseInstance: unittest.TestCase):
     # Call anywhere in the unit test methods (or in its 'setUp' method) as 'nameOfRunningTestMethod(self)':
     #   returns the _name_ of the running test method