By Terminate
Lancashire,
United Kingdom 
I have left my yucca plant outside and the trunk has gone soft at the top and it is drooping have I killed it
24 Jan, 2010
Answers
I agree, if the houseplant E elaphantipes, then you have terminated it :-)
25 Jan, 2010
Previous question
If you mean the houseplant type Yucca (Y. elephantipes) then yes, you have killed it. There is one other tender one, but all the others available here are hardy outdoor plants.
24 Jan, 2010