Is it forbidden to think about someone whose actions one admires, and how can one get rid of such thoughts?

There is no blame upon you for what occurred unintentionally and without choice, and which did not lead to falling into something forbidden, for Allah Almighty says: "And there is no blame upon you for that in which you have erred, but [only for] what your hearts intended." You must repel these thoughts, for they may lead to trials and indecencies. The heart desires and wishes, and it is obligatory to repel the fleeting thought before it becomes an idea, then a desire, then a resolve, then an action, then a habit.