running totals in Pivot Table - removing a user from the totals for the current week

Hi I am using running totals in my pivot table. We are tracking how many mobile devices are active. I use it for weekly reports. I don't copy all users each week - I simply add the new ones. For example, on July 26 we had 1,000 users (this is the first week we started tracking everyone that had registered in 2013). Then an additional 200 for Aug 2 (total 1,200), an additional 300 for Aug 9 (total 1,500), an additional 500 for Aug 16 (total 2,000). The question becomes - since I am not copying all users for each week - it would eventually become too many rows - how do I show when a user leaves the company? Specifically, reducing the week they left by one user. Versus deleting their name from the week they became active and having the numbers for that week - say Aug 2nd go down by one. I would really want it to be showing as one less in the Aug 23rd report.

Thanks.
Gayenell

FDibbins, thank you for taking a look. I tried to add another column to the data and use it in the pivot table, but could not figure out a way to make it work. Attached is sample data. For corporate my weekly running totals should be:
7/26/2013 72
8/02/2013 73
8/09/2013 74
8/16/2013 75
8/23/2013 74

I could not figure out how to get the 8/23/2013 row to reduce the corporate total by 1. Instead my corporate total added the deleted 1 to make a total of 76. I know it must be a simple change, but can not figure out how to make the pivot do the subtraction.

Instead my pivot creates this (which is probably better viewed in the attached spreadsheet):

Corporate Corporate Total
Active Left
72 0 72
73 0 73
74 0 74
75 0 75
75 1 76

Thank you for the idea. I did try a new column with 1's except where a user is deleted - I entered a -1. The problem becomes running totals - needed to drive the chart - if I don't include that column in my pivot table as a row or column label - then the pivot shows N/A. I have attached the newer version of the spreadsheet with the suggestion in case there is a way to play with it to get it to work.
The chart definitely needs running totals for each week.

Hi, I do want running totals for BYOD and Corporate using the row label of "report". But to get the column to include the subtraction of a device I have added "Active" Since it is not in the pivot table - I get N/A. I have tried putting Active under the column labels, but still no correct running table/chart. Please see the word doc with screenshots to see the variations on what I have tried, perhaps that would help.

I so apologize. I feel as if I am the one being dense. Would it be possible for you to attach the spreadsheet. With the running totals recogniznig the decline for Week Aug 23rd. I seem to be missing the point. Thanks.

Actually, I may get where we are disconnecting. The running totals would be each week. Aug 2nd would be 73 for Corporate, Aug 9 is 74, Aug 16 is 75 and Aug 23 would be 74. I really would not need a grand total row. Is that where we are tripping each other up?

Your right - yours looks perfect. I will disect it to figure out the differences. Thank you so much for helping. I will mark the problem solved. I really appreciate all your help.