To force AirWave to poll a device ->
Go to a controller and choose the 'poll now' option.
To do this in bulk, you will want to go to a list view that can list all controllers, then use the 'modify devices' link above the device list table -> this will get you checkboxes in which you can check all controllers and then issue a poll now from the options below the device list table.
Then to report it, create a new Device Inventory Report -> run it from '1 hour ago' to 'now' to get an image of the last hour. Note that all device pollings must be complete for the report to be accurate, some devices take longer than 2 minutes to poll -> you will see polling status on the controller's monitor page above the device info box.
Purging data is done by editing historical data values, and then initializing the database clean up. This is not a recommended path as the older data may be desired to compare to the new data.