To delete Purchases, go to the All Purchases view, search for the target purchases, select them and click on the DELETE button. Note that if any of these purchases are linked to a software license, the Purchase count of that license will be reduced.
You can delete Inventory Devices, you can perform a similar process from the Active Inventory or All Inventory views. However, keep in mind the source of data that created that inventory device. For example, if the inventory device was imported from SCCM, you can delete the device from FNMS - but if that device is still active in SCCM, then the next time inventory is imported from SCCM the inventory device will be created again within FNMS.
