Add functionality for delete command

[joshiayush]

Description

inb/inb/inbparser/command.py

Lines 357 to 374 in 2f66b3a

	def delete(self: Command) -> None:
	"""Method `delete()` deletes user's information from database.
	This feature is not programed yet. Contributions are welcome.
	Args:
	self: (Command) Self.
	Example:
	>>> from argparse import Namespace
	>>> from inbparser import Command
	>>>
	>>> namespace = Namespace(which='delete', keyword='email') # Not designed yet
	>>> command = Command(namespace)
	>>> command.delete()
	>>> # -> It should remove values from database
	"""
	self.logger.info("facility not present")

As of now command delete which is meant to delete the user's information from the database or the entire database, does not work. It will be a good feature to implement in conjunction with config command to give user's the ability to create and remove database entries or to remove the entire database with the help of the delete command.

Possible solutions

1. Check if we have write permissions.
2. Check if database exists, if yes then follow step 3.
3. If requested to delete entries, delete the entries using the Python SQLite API using which the database was created.
4. If requested to delete the entire database, execute rm -f command on the database.