Not sure there's really much to say on this.  Simon states the following is all that's needed:

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Code wise it seems very simple.

a) Mark the field as obsolete in the admin section
b) Disable the issuetracker extension[1]
c) Remove the four places that cf_issuetracker appears in the core
code.[2]
d) Test
...
f) Profit :)

 -- simon
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