DE-ACTIVATING THE ACCOUNT
In the account dimension, you can assign "Not Required" in one of the 'Vary By Scenario Type And Time' attributes (e.g., Text1). And you can make that assignment time and/or scenario dependent. So for example, account 1234 is "Not Required" 2019M1 and forward, while account 4567 is "Not Required" 2020M1 and forward.
REPORTING DE-ACTIVATED VALUES
Set the Dashboard with a dynamic time period, and filter for Account Text1 = Not Required. When the dashboard is run in 2019, account 1234 values would be included. When the dashboard is run for 2020M3, account 1234 + 45467 values will be included.
RE-ACTIVATING
To re-activate account 1234 in 2020M6, set the Text1 field in that period to "Required".
