How to remove double quotes from outputlookup csv file
you cannot remove double quotes from output lookup csv file.
Splunk will put them around any values containing any non alphanumeric character. See this answer for more details http://answers.splunk.com/answers/114632/when-does-splunk-add-double-quotation-in-outputcsv.html
Anyhow, why is this a problem to you?
Can't you simply use something like this on the lookup fields:
... | head 1 | eval foo="\"quotes\"" | eval boo=trim(foo, "\"") | table foo boo