I will be glad to assist you with this. The script below will delete all of the test runs from the specified testset folder. Make sure you have the correct Excel add-in installed on your machine. You will also need to make sure you install the Connectivity addin and register the ALM Client on your machine as well. If you have any questions or concerns, please let me know.
    Sub PurgeTestRuns()
        Dim TSetFact
        Dim tsFilter
        Dim KeepLast
        Dim DateUnit
        Dim UnitCount
        Dim StepsOnly
        Dim runFact
        Dim runFilter
        Dim tsTest
        Set tdc = CreateObject(''TDApiOle80.TDConnection'')
        tdc.InitConnectionEx ''http://your_alm_server_name:8080/qcbin''
        tdc.Login ''your_alm_username'', ''your_alm_password''
        tdc.Connect ''your_alm_domain'', ''your_alm_testset_folder''
        'Set filter for tests in folder specified.
        Set TSetFact = tdc.TestSetFactory
        Set tsFilter = TSetFact.Filter
        'If project name contains any spaces, use 3 sets of double quotes (i.e. ''''''My Test Project'''''').
        'If there are no spaces, use a single set of double quotes instead (i.e. ''My_Test_Project'')
        tsFilter.Filter(''CY_CYCLE'') = ''Your_ALM_TestSet_Folder''
        'Set filter for tests with a No Run status.
        Set runFact = tdc.RunFactory
        Set runFilter = runFact.Filter
        'If the test status contains any spaces, use 3 sets of double quotes (i.e. ''''''No Run'''''').
        'If there are no spaces, use a single set of double quotes instead (i.e. ''Passed'')
        'runFilter.Filter(''RN_STATUS'') = ''''''No Run''''''
        'KeepLast will keep the amount of test runs with the status type that was selected to be deleted in the
        'runFilter.Filter line above. Example - If there are three test runs with the status of Failed,
        'and you set KeepLast to 2, it will only delete one of those test runs.
        KeepLast = 0 'Keeps the set amount of status types not to be deleted
        DateUnit = 1 'Days
        UnitCount = 0 'Purge starting 0 days ago (as I was testing with today's Runs)
        StepsOnly = False ' Purge both the runs and steps.
        'Purge the runs.
        tdc.PurgeRuns2 tsFilter.Text, runFilter.Text, CInt(KeepLast), CInt(DateUnit), CInt(UnitCount), StepsOnly
        MsgBox ''Purge Completed!''
        'Disconnect from the project and dispose all objects to free memory and the session
        tdc.Disconnect
        tdc.Logout
        Set tdc = Nothing
        Set TSetFact = Nothing
        Set tsFilter = Nothing
        Set runFact = Nothing
        Set runFilter = Nothing
    End Sub