Can someone help me modify my script? To exit sub on error after line 7?

You can use On error resume next.

As you should use this very carefully it is recommended to always comment, why you think it is ok to use On error resume next in this case. And reset the error handling as soon as possible by inserting On error goto 0 or On error goto xxx

Sub shutdownbot()

Application.ScreenUpdating = False
Application.Calculation = Application.Calculation =xlCalculationManual
Application.DisplayAlerts = False
Application.EnableEvents = False
Windows("FlaggingreportBOTv2.xlsb").Activate  

‘when the end user opens the file I expect this line to error then exit the sun with any error messages on screen being supressed

On error resume next
Windows("Post 7am routing risk level v5.2.xlsb").Activate. 
On error goto 0

Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual
Application.DisplayAlerts = False
Application.EnableEvents = False

End sub