I am trying to edit the table in Schedule C ,Part V. There are existing categories from last year however I cannot enter amounts without creating a new line. Bug?

You will not be able to edit directly on the Schedule C, Part V itself to remove or edit the "other expenses" that appear there if they transferred in from your 2016 return or came in from the Schedule C Worksheet.  

There 2 ways to proceed:

The entries you see on Schedule C, Part V that you can't edit come from the Schedule C Worksheet.

1. While in Forms Mode, look in the left column list of forms, and select the Schedule C Worksheet (may be abbreviated as 'Schedule C Wks').    On the Worksheet, you can scroll way down to   "Miscellaneous Expenses", and then in that subtopic scroll further down to "Other expenses".   You should be able to edit/delete there on the Worksheet.   Then check the Schedule C, Part V to be sure your changes flowed correctly to the Schedule C.
2. The other way would be to use the interview mode (step by step).   Other Expenses entered from interview mode flow first to the Schedule C Worksheet, and then to Schedule C, Part V.  If you have problems, use option 1.  

The amount for Utilities, Line 25 on Schedule C is wrong on the form.  I used the step by step, and Utilities $ is not the same.  I would like to know where the number flowed from in case it belongs somewhere else.  I'll check the Schedule C Worksheet, maybe that will work since the Step by Step did not.