Multi Mapping with Dynamic FileName - how to remove the target field which is used for variable substitution in SFTP Adapter

HI All.

i hope we unable to achieve dynamic configuration in multi mapping, so we followed below link.

so now we're trying to achieve using variable substitution. my scenario is JDBC to SFTP, but below mentioned link pointing to FCC.

Multi Mapping with Dynamic FileName and Dynamic Folder using Variable Substitution

i've done variable substitution and it's working file,  can you please suggest how can i remove the field  which i used for variable substitution in receiver SFTP adapter level?

Regards

Ramesh