Here are the instructions on how to perform factory reset for Samsung Galaxy SM-T350 tablet, since there is no other way of removing the password ***** forgotten.
1. Completely turn off the tablet by pressing and holding down the Power button
2. Once the tablet has been turned off, press and hold down the Volume Up, Home and Power buttons at the same time
3. Continue to hold those 3 buttons and the tablet will turn on. Once you see the Samsung logo appeared on the screen, release the buttons
4. You will then see the Android system recovery menu. There select wipe data / factory reset by using the Volume buttons to navigate up and down, and Power button to confirm
5. On the next screen, select Yes -- delete all user data to confirm the factory reset
6. Wait until the reset has been completed. When the Android system recovery menu appears again, select reboot system now
7. The tablet will then restart and load default settings. You will need to set it up from the start, but there won't be any password ***** time
Let me know if the instructions worked for you, or if you have further questions.