[pco]

Either radio buttons or a single checkbox in User Options, here's single checkbox:
In admincp make a new user profile field called say "Use Quick Edit" Type "Multiple Selection Checkbox", press continue. Enter description of your choice and in the field Options just add 1 Option called "No" (without the quotes). Edit the other field options as required ie. "field editable by user YES" but "not shown on memberlist" etc. Set the "Display page" to "Options: other", then press save and read what the field number is for this field, ie. field8. Now edit the postbit(_legacy) template(s) and change the line(s) starting with

<if condition="THIS_SCRIPT=='showthread' and $post['editlink'] and $bbuserinfo[userid]>0">

to this

<if condition="THIS_SCRIPT=='showthread' and !$post['field8'] and $post['editlink'] and $bbuserinfo[userid]>0">

Additionally put this around your showthread_quickedit template:

line 1: 
<if condition="!$post['field8']">

last line:
</if>

Don't forget to change the 8 from above to your field number.

The Quick Edit will still be switched on now for everyone in their profiles by default. Those who want to have it off/not loaded anymore have to tick the "No" box in their UserCP Options to get rid of it. If you want to have it the other way round(Quick Edit off for everyone by default) then name the Quick Edit field Option "Yes" and not "No" and remove the exclamation marks:

!$post['field8']

becomes

$post['field8']

Good luck