Hi,
If you are using the CL_GUI_SPLITTER_CONTAINER to split the container then the method
SET_ROW_SASH can be used to remove the splitter
DATA o_spli TYPE REF TO cl_gui_splitter_container.
CALL METHOD o_spli->set_row_sash
EXPORTING
id = 2
type = o_spli->type_sashvisible " to disply sash in container
value = o_spli->false " true-visible
EXCEPTIONS " fale-invisible
cntl_error = 1
cntl_system_error = 2
OTHERS = 3.
IF sy-subrc <> 0.
MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.
Hope this helps