Cleanup after debconf-set-selections - no interaction installation

I have a problem with debconf-set-selections command. After I install percona server on my machine root password is located in several cache files. I am not sure if i can just delete this files or entire directory.

root@testing:/var/cache/debconf# grep -ir 'superpassword' .
./passwords.dat:Value: superpassword
./passwords.dat:Value: superpassword
./templates.dat-old:Default: superpassword
./templates.dat-old:Default: superpassword
./templates.dat:Default: superpassword
./templates.dat:Default: superpassword

So my question would be how to properly clean these files from root password?