You can use replaceNode()
on the node that is needed to be removed. It applies to all Teachers
nodes under Classes
parent.
import groovy.xml.XmlUtil
def xml = '''
<School>
<Classes>
<Class>
<Teachers>
<Name>Rama</Name>
<Name>Indhu</Name>
</Teachers>
<Name>Anil</Name>
<RollNumber>16</RollNumber>
</Class>
<Class>
<Teachers>
<Name>Nisha</Name>
<Name>Ram</Name>
</Teachers>
<Name>manu</Name>
<RollNumber>21</RollNumber>
</Class>
</Classes>
</School>
'''
def parsed = new XmlSlurper().parseText( xml )
//Remove all Teachers node
parsed.Classes.Class.Teachers.replaceNode { }
XmlUtil.serialize( parsed )