Siemens 2000 - Manual (Page 53)

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53
Deleting a certificate
Open the Select a certificate list with the certificates stored on the
handset and select the certificate you wish to delete.
Click the Delete button. The selected certificate is deleted from the
handset.
If there is not enough memory in the handset for importing a new
format you will receive an appropriate message. You should then
delete any certificates, pictures or melodies you no longer require to
free up sufficient memory (see Æ File System).