how to add a new css style onclick in a webpage

how to add a new css style onclick in a webpage

i want to add button to change styles as like below...
default: textarea { resize:vertical; }
onlick: textarea { resize:none; }
please help me how to add this because i dont want to show textarea resize
symbol while print and i want to add resize option while entering text.
because when print option is clicked it is showing textarea resize symbol
in the pdf document, i dont want to want to show it so i want to add
remove button before clicking print option.