Perform these steps to downgrade an Adaptive Server versions 15.7 and later if you enabled 256-bit key encryption keys.
alter encryption key keyname [with passwd password modify encryption with no dual_control
sp_encryption system_encr_passwd, <password>
alter encryption key keyname with passwd master key modify encryption with passwd system_encr_passwd
alter encryption key keyname with passwd old_password modify encryption with passwd new_passwd