Turbotax is filling my non-resident Louisiana return with my federal business income, which was derived in Texas. How do I delete the Texas income from the La return?

In the State returns section, most likely manually. Are you using an online or desktop version of TurboTax?

I'm not specifically familiar with the LA software.  But, it works the same in most states: you manually allocate the portion  of each source of income (e.g. business) to LA, in the state ( LA) section of TurboTax.