This article discusses how to exclude multiple Value from a Dimension Filter.
You basically have two methods for excluding values. One is the <> does not equal operator and the other is the Not statement. With the <> does not equal you can exclude only one value. If you want to exclude multiple values you must use the Not statement. You can see in this example an RQL error in the statement of <> 9010:9999
To fix this you need to use the not statement. Here you see the Not statement or if you use another Dimension you would use the And Not Statement with the Range of Accounts
Report Designer, Not, Operators