delete attribute from gal

[asalar]

how to delete value of attribute 'email2' (in ldap: zimbraMailAlias) from GAL e.g:
zmprov sg example.com test
# name id
zimbraId: c0873e16-9881-435c-8c1d-4ed0863bdb7b
createTimeStamp: 20170101121132Z
email: test1@example.com
email2: test1@example1.com

# name id
zimbraId: 5e400d22-3c43-4e60-835a-f5cfc4f983d3
createTimeStamp: 20170101121137Z
email: test@example.com
email2: test@example1.com

i want delete email2 from the user specified in the above example.

[asalar]

I rename domain with zmprov rd from 'example.com' to 'example1.com' and defined alias for the old domain (example.com). I want the emails that point to the old domain to not display in GAL. For this reason, according to the following link:
https://wiki.zimbra.com/wiki/GAL_Attribute_Mapping
I changed all the attributes in left to the attribute 'zimbraMailDeliveryAddress'.I did this to make values of 'email' & 'meail2' the same as values for the user with domain 'example1.com'. But this was not happen & value of 'email2' is the same as in alias. What did I do wrong?
zimbraGalLdapAttrMap: zimbraMailDeliveryAddress,zimbraMailAlias,mail=email,email2,email3,email4,email5,email6
change to:
zimbraGalLdapAttrMap: zimbraMailDeliveryAddress,zimbraMailDeliveryAddress,zimbraMailDeliveryAddress=email,email2,email3,email4,email5,email6

Can I delete values from MySql instead of LDAP? Can I use zmmailbox command?