To remove those lost and found objects you may try the following options:
Option # 1:If those GPOs and OUs that are in the lost and found container no longer exist, then you may right-click and select the option "Unregister and Remove History".
Option # 2:The other option is to delete records from the
ObjectData table in GPOADmin database manually. For this you may:
1- Open SQL Server Management Studio (SSMS).
2- Take a database backup.
3- Right-click your GPOADmin database and select New Query.
4- Run
select * from ObjectData where Name ='ObjectName'. You would have to replace ObjectName with the name of the object found under lost and found container.

5- If the command shows a record for the object, then you may delete the record by running
delete from ObjectData where Name ='ObjectName' by replacing objectname with the name of the record that you want to delete.

You may repeat the same steps to delete other objects under lost and found container.
NOTE: The information in the script(s) provided is known to work successfully; however, they have not been officially tested by Quest Quality Control. If any of these instructions are changed and/or incorrectly used, intentionally or unintentionally, this solution becomes unsupported by Quest Software Support and Development. Quest Support and Development recommends always to make a backup of the current database prior to execution of any script(s) that may modify it.