Meh . The cool kids are on tumblr anyway 8)
Besides, your doing it all wrong. You send out a message saying that you are having problems with spam accounts, or that you are being forced to rethink your Twitter account due to an upgrade in Social Media security at work ( this of course depends an where you work, for me it’s actually a very real thing ).
This then gives you a reasonable explanation as to why you a having a ‘cull’, without then putting other peoples noses out of joint, regardless of whether you wish to or not. You can always add ,that you may be creating a separate ‘personal’ account later, and you will re-follow them at a later date.
You can then delete away without ruffling feathers.
Oh the social politics you have to negotiate in the 21st Century. 🙄