I really would like to be able to delete the develop presets that ships with LR3. I don't use them as they are in the way of my own presets when using the Library Module.
"How can i delete the preset lightroom export presets (ie 'for email, 'burn full size') i only want the user presets."
You cannot 'Delete' but you can Minimize by clicking the 'spinner' triangles-
"Also if i tick my user presetm i cant adjust it, its all greyed out."
DO NOT TICK ANY PRESET unless you want to 'Batch' multiple Export Presets in the one operation.
Simply [mouse left-click] on the Preset NAME for the ONE preset that you want to use or edit.
Unfortunately, Watermark 'position' is fixed in a Watermark Preset so you need to either create an Export Preset for each Watermark preset, or change the Watermark Preset in the one Export Preset.