Go to SUB ACCOUNTS and add the following code in the field "Control panel custom CSS" for the sub account:
.icon-suitcase, .b24btn_AddBooking{display: none}
If you want to hide a certain setting box on a page add the following code in the "Control panel custom CSS" for the sub account for example:
.pagetypecommunicationbooktemplate #settingformid .background_boxprop:nth-of-type(2) { display:none; }