The Wikipedia infobox gives no established or founding date field value; the article history section only fixes a British trading station from 1898 and formal administrative control from 1906, dates for colonial activity rather than the founding of the settlement itself.
What would resolve this A cited historical source giving a founding or first-settlement date for Warri, distinct from the 1898 trading post and 1906 administrative dates already on record.
OpenhistoryWarri (Wikipedia)