awk     'NR==1,/<rs:data>/
         /<\/rs:data>/          {P=0
                                 delete TAIL
                                 CNT=0
                                }
         P
         !P                     {TAIL[++CNT]=$0}
         /<rs:data>/            {P=1}
         END                    {for (n=1; n<=CNT; n++) print TAIL[n]}
        ' file
<?xml version="1.0" encoding="utf-8"?>
<xml xmlns:s='uuid:XYZ'
     xmlns:dt='uuid:ABC'
     xmlns:rs='urn:schemas-microsoft-com:rowset'
     xmlns:z='#RowsetSchema'>
<s:Schema id='RowsetSchema'>
   <s:ElementType name='row' content='eltOnly' rs:CommandTimeout='30'>
      <s:AttributeType name='First_Name' rs:name='First_Name' rs:number='1'>
         <s:datatype dt:type='string' dt:maxLength='100' />
      </s:AttributeType>
      <s:AttributeType name='Hospital_Name' rs:name='Hospital_Name' rs:number='2'>
         <s:datatype dt:type='string' dt:maxLength='100' />
      </s:AttributeType>
      <s:AttributeType name='Dept_Name' rs:name='Dept_Name' rs:number='3'>
         <s:datatype dt:type='string' dt:maxLength='100' />
      </s:AttributeType>
   </s:ElementType>
</s:Schema>
<rs:data>
   <z:First_Name='John Doe' Hospital_Name='XYZ Hospital' Dept_Name='Heart Health' />  
    <z:First_Name='Jane Doe' Hospital_Name='XYZ Hospital' Dept_Name='Maternity' /> 
</rs:data>
</xml>