"Our duty is to make Turks out of all the non-Turks within the Turkish country, no matter what. We will cut out and throw away any element that will oppose Turks and Turkishness." There's no such quote from İnönü. But when lies are supported with such strong words, suddenly people start respecting them.
These lies are made up by kurd-islamists in recent years, and other groups such as armenians are also trying to grab a bite from Turkey, by taking kurd-islamists side and supporting their lies. These lies can easily be traced back to kurd-islamist so-called historians' books, but one can go no further than that, for there's no supporting evidence on their claims even in their books.
But as always, if you repeat the same lies over and over again, people will believe it.