Add backspace button

[SaadOps]

Added a backspace button successfully which cuts numbers one by one and clears the input field if it contains a string.

89 Resolved

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[DhanushNehru]

Please resolve the merge conflicts @SaadOps

[SaadOps]

Please resolve the merge conflicts @SaadOps

Done :)

[selemondev]

Thank you @SaadOps for your contribution.