TheChanger
Warlord
--Deleting Techs, Policies and Buildings appears to be impossilbe (even when replaced by exact duplicates)
Deleting techs is possible, and lemmy101 made a tool to help make tech trees in a much simpler visual way:
http://forums.civfanatics.com/showthread.php?t=395209
EDIT: ahh the reason for the crashes and why the above link works:
http://forums.civfanatics.com/showthread.php?t=395922