Hi,
Thank you for posting your query on Symantec community.
SEP SBE does have the option to put on an uninstall password. It looks additional security on the client is setup by admin.
Either Administrator can remove it through the management console or need cleanwipe tool. Cleanwipe tool can wipe out SEP client completely though password is in place.
Can you contact SEP Admin? OR Do you have an access to download latest Cleanwipe from Here.