Set the text background color to None. Note that it is not white, it is colorless. Then right-click the text box and select Set as Default Shape Format. The next time you insert a text box, it won't be there.

10 1 Education PPT is a lesson preparation software developed by NetDragon Network Company to serve teachers and users. It contains millions of teaching resources and courseware materials that fit the textbook version, and can realize one-click lesson preparation. The software provides teaching tools, interactive teaching tools and 3D resources to assist teachers in teaching.