The best way to avoid confrontation is simply to be unavailable - don't return phone-calls, always be busy when asked out, don't be keen to chat, avoid beng in the places where your 'suitor' can find you. This may provoke a 'Are you avoiding me?' question, in which case you can proceed to confirm that fact with as much, or as little tact, as you feel is necessary. Although you may not want to pursue a relationship, put yourelf in your suitor's position, and try to let them down gently. If you can let the other person walk away with their self respect intact, it's the nicest way to let them down gently.