The move comes following a surprise inspection at the schools in Rajasthan and Delhi in September during which several lapses were found, they said.
"The practice of dummy or non-attending admissions contradicts the core mission of school education, compromising students' foundational growth. To address this issue, we are taking a decisive action to combat the proliferation of dummy schools and send a clear message to all affiliated institutions to resist the lure of accepting dummy or non-attending admissions," CBSE Secretary Himanshu Gupta said.
He said the vital observations of the surprise inspection committees regarding the irregularities observed during the inspections were communicated as a report to the respective schools.
"The replies submitted by the schools were examined in detail by the Board. Based on the inspection findings and supported by videographic evidence, affiliation of 21 schools was withdrawn and six schools were downgraded from senior secondary to secondary level," he added.
Of the 21 schools whose affiliation has been withdrawn, 16 are in Delhi while five of them are in Rajasthan's coaching hubs -- Kota and Sikar.