You can't do what you want with LR's built-in features, and I don't know of an plugins that will do precisely what you want either. Why do you want to suppress the person keywords anyway?
LR represents a named face using XMP regions (which specify face rectangles and include the names of the faces), the field XMP:PersonInImage, and keywords, which get stored in XMP:Subject, XMP:HierarchicalSubject, and IPTC:Keywords. You can suppress all person information using the Export option Remove Person Info. You can suppress all of one particular person's information (including face regions) by editing the keyword in the Keyword List and unchecking the option Include On Export. You can suppress XMP:HierarchicalSubject using the export option Write Keywords As Lightroom Hierarchy. But you can't suppress XMP:Subject, IPTC:Keywords, and XMP:PersonInImage without also suppressing the XMP regions.
You could use the Metadata Wrangler plugin or the Run Any Command plugin (combined with Exiftool) to strip out all keywords after export, but they can't distinguish between people keywords and non-people keywords. So if you want non-person keywords exported while stripping out person keywords, they can't do it.
Thank you for the detailed explanation. The only reason for I want to suppress the person keywords in the general keywords is because I don't see why should I store redundant data
There's not much practical downside to the redundancy (the extra bytes are a tiny fraction of percent of the total file size). There are some practical advantages in general -- the industry-standard metadata standards are a legacy mess, and LR's use of them increases the likelihood that at least some of the face-tagging information will be readable by other apps. (Not many apps read the XMP regions, and even those that do can be incompatible, e.g. Picasa and LR.)