FL Studio provides several ways to stop a sample from playing. One way is to use the 'Tape Stop' effect, which simulates the sound of a tape being stopped abruptly. To use the Tape Stop effect, insert it into the channel where you want it to apply. Then open the Effect Editor for that channel and locate the 'Tape Stop' effect under the 'Time' category. In the Effect Editor, set the Start Point and End Point sliders to determine how much the sample will be played. The shorter the sample will be, the farther you move these sliders towards either end of the timeline. You can also set a Curve for how quickly or slowly the sample will play from the Start Point to the End Point. Finally, adjust the Volume and Panning sliders to get the desired sound. You can also use the other controls in the Effect Editor to further customize the sound of your tape stop. Click the 'Apply' button to hear the effect when you're done.