It is a fact that Thomson Reuters’ JCR Impact Factor is the most reliable and authentic one, and is the only measure that is considered for the purposes of academic evaluation. Other metrics such as the Scientific Journal Impact Factor (SJIF), Universal Impact Factor (UIF), Global Impact Factor (GIF), etc. are products of other indexing companies. Most reputable journals prefer to get indexed in JCR. Thus, as you have rightly said, for most academic purposes such as selection for academic interviews, awarding tenure, etc., SJIF will not be considered.
Since you wish to withdraw your paper from this journal, you will have to send an email to the journal to stop further processing of your paper immediately and explain that you wish to withdraw the paper. The journal might not readily agree to the withdrawal as the paper has already been accepted, but you will have to apologize and request them to comply. Note that the withdrawal process will be complete only after you receive the confirmation of withdrawal from the editor; hence, you will have to follow up with them. Do not submit your paper to another journal before you receive confirmation of withdrawal: this can be considered as duplicate submission.
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