Unfortunately, assets deleted by the database cleanup options are not logged in the database.
In general, user configuration changes can be found in the built-in report: "Users: Changes made to Lansweeper configuration".
If you manually delete the assets then the action is logged and you can use the report below:
Select Top 1000000 Count(tblConfigLog.LogID) As AssetDeleteCount,
DatePart(mm, tblConfigLog.Date) As Month,
DatePart(yyyy, tblConfigLog.Date) As Year
From tblConfigLog
Where tblConfigLog.Description Like 'Deleted asset with name%'
Group By DatePart(mm, tblConfigLog.Date),
DatePart(yyyy, tblConfigLog.Date),
tblConfigLog.Description
Order By Year Desc,
Month Desc