Thank you for your question. The imaginative faculty corresponds to two Arabic terms of which one is general called the khayāland the other is more specific known as the wahm. The khayāl doesn’t have a negative connotation as the imagination can be used for good and bad and at the same time can either be connected to reality or disconnected from it. Truthful dreams are sensed by the khayāl as well as the unveilings of the ʿurafāʾ. However, when the imaginative faculty is referred to in its negative sense alone it is called the wahm. That is the imagination that is used for bad and disconnected from reality.
When the imagination is referred to negatively in Islamic literature it is a reference to the wahm, not to the khayāl as a whole. The wahm needs to be refined so that the imaginative faculty is free from being used by the base desires and anger to achieve their goals. That is that the imaginative faculty is used by the lower self to achieve what it wants and this has to be controlled and finally stopped. Refinement at the last stages is very sophisticated and detailed. This is the meaning of the wahm coming under the control of the intellect as the intellect is that faculty which is connected to reality, always calls to what is right and is detached from the lower self. The reality of the intellect is a lengthy topic.
As for the practical method of controlling the wahm, since all what has been spoken about refers to the inner aspect of the human, the first step is self-awareness. You cannot control something that you cannot detect. It is to pass by the terminology and see the wahm active within the self by understanding one’s own commanding self and watching how the imaginative faculty is used. The terms are there to help you identify the propensities within yourself. Then it is to reject all that is wrong within yourself and work to its improvement. There are other interrelated things that a person needs to do but this is the most fundamental. It has been expressed by some ʿurafāʾ as the process of mushāraṭat (putting conditions on one’s self), murāqabat (watching over one’s self) and muḥāsabat (taking one’s self to account). Some ʿurafāʾ have particularly stressed murāqabat and this is self-awareness.
May Allah make you successful. One who sincerely purifies himself has the love and satisfaction of Allah and all of the awliyāʾ of Allah. So continue, may Allah make you successful.
'Abd Allah Esmail