The alter login profile command can be used to add, drop or change attributes of a login profile and their corresponding values. If the attributes have not been specified, they will be added to the login profile. See “Login Profile Attributes” for a list of login profile attributes.
The following example removes the login script attribute from the login profile mgr_lp. If a login script is specified for the default login profile, it will be invoked on login, otherwise no login script will be invoked.
alter login profile mgr_lp drop login script
See alter login profile in the Reference Manual: Commands for complete syntax.