To uninstall and decommission the product you may do the following:
1- From Configuration Manager make sure no discovery is running. If there is a discovery that is running, then cancel that task. To cancel a task click the discovery to select it,
then click "View Queue" on the top and then click cancel.

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2- Uninstall all existing nodes from your clusters. To do this, select one cluster, then go to the nodes tab, then select all nodes and then click "Disable Node". Once all nodes are disabled, click "Remove Node".

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3- Close Configuration Manager console, then uninstall the product from Programs & Features, or from Control Panel.
4- After the program is uninstalled, validate to confirm that the following directories were deleted as a result of the uninstall process. If they were not removed, then proceed to delete those manually:
C:\Program Files\Quest\Enterprise Reporter
C:\ProgramData\Quest\Enterprise_Reporter5- Login to the SQL Server using SQL Server Management Studio (SSMS) and remove roles, logins, and delete your ER database (You would have to confirm if you may proceed with this right away based on your organization's offboarding or decommission policy). If you don't have access to the SQL server that hosts ER database, then you would have to contact a DBA to perform the following:
5.1- Once you loggin to SSMS, expand databases > ER database > Security > Roles > Database Roles. Then right-click and delete the following roles: Discovery_Admin_Role, Discovery_Node_Role, Reporting_Admin_Role, and Reporting_Operator_Role.

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5.2- Expand databases > ER database > Security > Users and right-click delete all reporter users.

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5.3- Now, below "Databases" on the very top, you will see "Security". Expand Security, then logins and delete all reporter groups listed here.

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5.4- Expand "Databases" again and delete Enterprise Reporter database.

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6- Remove the following AD security groups from your Enterprise Reporter service account, then once removed proceed to delete them (This will depend in your organization offboarding policy, you would have to confirm internally with management, AD team, or security team if you may delete these groups right away or if you would have to keep them around for a while before deleting them).

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7- Disable or Delete your Enterprise Reporter service account. Again, these actions would depend in your organization's offboarding or decommission policy.
Additional (optional) you may also search for the word "Enterprise Reporter" in your ER server registry to delete any left overs from the registry of the uninstall process.