XF 2.0 How to resize already uploaded images?

[Mackeral_Fillet]

I have a few 4mb+ images that have been uploaded and attached.

How can I resize these and optimise them? Don't really want massive attachments (I have since changed the settings via ACP to limit this).

 

[webbouk]

https://www.xf2addons.com/resources/resize.32/