If you have qualified CTET under the OBC-NCL category but applied for the EMRS TGT post as a General category candidate, your candidature is generally not rejected only because the categories are different. What matters for EMRS recruitment is the category you selected at the time of filling the EMRS
If you cleared CTET in 2018 under the OBC-NCL category, that certificate remains valid for eligibility as long as CTET validity rules allow it. However, for KVS PRT recruitment, your category is decided based on your current OBC-NCL status, not the one you had in 2018. Since you mentioned that