that command should clean up any opera file you have left. If it fails, you may have to use the --force option. I'm not sure how erasing the files manually affects the rpm process. After that, you should be able to install opera with ...
rpm -i opera-8.54-20060330.6-shared-qt.i386-en.rpm
The -U and --force switches might force an upgrade of opera, but again, I'm not familiar with how erasing previous files affect the rpm process.