Trying to remove data from graph

hey
i am trying to remove all data from a graph based on user data that they logged,

am i on the right track? i am not sure if i used the removeObjectFromKey method right..

obviously this does not work, i am just looking for some direction.

Code:

	if ([[[sender titleLabel] text] isEqualToString:@"Reset"]) {
		if ([[[NSUserDefaults standardUserDefaults] arrayForKey:@"ResetData"] count] > 1) {
			NSMutableArray *ResetArray = [[NSMutableArray alloc] initWithArray:
										 [[NSUserDefaults standardUserDefaults] arrayForKey:@"ResetData"]];
			[ResetArray removeObjectForKey];
			[[NSUserDefaults standardUserDefaults] setObject:undoArray forKey:@"ResetData"];
			[ResetArray release];
			ResetArray = [[NSMutableArray alloc] initWithArray:
						 [[NSUserDefaults standardUserDefaults] arrayForKey:@"LoggedWeights"]];
			[ResetArray removeObjectForKey];
			[[NSUserDefaults standardUserDefaults] setObject:undoArray forKey:@"LoggedWeights"];
			[[NSUserDefaults standardUserDefaults] synchronize];
			[ResetArray release];
			[graphView reloadData];
			
	
		}
		
	}