If you've forgotten your Samsung Galaxy Tab screen password, you can use the Find My Device website to factory reset your device:
Go to the Find My Device website
Enter your Google account email and password
Select the device you want to reset
Click ERASE DEVICE on the left panel
Confirm the erasure
Verify your Google account
Click Erase to confirm the erasure of your device's data
Choose Use my Google Account to set up your device
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