How can one get rid of the dubiousness of money resulting from a previous job in selling cigarettes, and is it necessary to dispose of all properties purchased with this money, and what is the ruling on money acquired from a lawful job when using clothes or eating food purchased with dubious money?

We ask Allah to cure you of the whispers (waswas), and its treatment is to ignore it and seek refuge in Allah from it. What you gained from your previous work, from which you have repented, is permissible for you, and you are not required to dispose of it; because you did not know the prohibition of selling cigarettes, and your work was not limited to selling them, rather it was one commodity among many in the shop. All of this is merely a whisper, so ignore it and benefit from your possessions. If you wish to donate them because you do not need them, there is no harm in that.