This Ruby script removes all local and remote tags in a single-line way, so you don't need supply your credentials several times. Optionally, you can remove only tags greater than a specific version.

clear_tags.rb

#!/usr/bin/env ruby

# Only tags >= min_tag will be removed.
min_tag = '0.0.0'
tags = `git tag`.split(/\s+/).select do |t|
  Gem::Version.new(t) >= Gem::Version.new(min_tag)
end

`git tag -d #{tags.join ' '}`
`git push origin #{tags.map { |t| ':' + t }.join ' '}`