Hello @kartik,
One of the methods it provides is tokens(), which defines a hasMany relationship between Laravel\Passport\Token and models using the trait. You can use this to retrieve a list of all of the tokens for a given user:
$userTokens = $userInstance->tokens;
The token model itself has a revoke method:
foreach($userTokens as $token) {
$token->revoke();
}
Hope it helps!!