Hi @Patrick Picard
I don't know if it still relevant for you but as far as i know it is possible to kill llap queries from HDP 2.6.3 and above.
Using the following:
1. Identify the query which needs to be killed
2. Using beeline, connect to LLAP
3. execute the command below in beeline
# kill query "<hive query ID>"
The command would be for example
# kill query "hive_20180104093525_f90a6496-42fc-46bb-8e4a-8edc638b193d"
I haven't tried it myself but it should do the trick.