In case you need to manually truncate the database logs of your Exchange server, you can follow the steps below. You'll need sufficient permissions and access to the Exchange Management Shell.
Get-MailboxDatabase | Select Name,EdbFilePath,LogFolderPath
You'll notice the database name, which you need to mount/dismount the database, and the physical location of the database, specified by the value of EdbFilePath. The value LogFolderPath reveals the location of the Exchange database logs, which you will be truncating in a short while.
Dismount-Database "Mailbox Database Name"
eseutil /MH "drive:\path-to\database.edb"
The output of the command will tell you whether the database has been shut down cleanly. Fairly at the top, look for a field that says State:. If it says Clean Shutdown, then you can go ahead with the next step.
If it doesn't say Clean Shutdown, the database is still in use, or shut down dirty, and you can't truncate the Exchange logs!!
Mount-Database "Mailbox Database Name"
Get-MailboxDatabase -Status "Mailbox Database Name" | Select Name,Mounted
The value of Mounted should be True.
Test-MAPIConnectivity -Database "Mailbox Database Name"
If the value of Result is Success and there are no errors, the database is succesfully mounted again, and clients can access it.
If you have more than one database, you can repeat the steps to perform manual truncate of all of them.