SQL dynamic query: check whether table column has any data

I do have dynamically generated tables list, user can modify those tables ex: add columns and remove columns, add data etc..

I need to modify this stored procedure, when user needs to drop particular column from specific table, there I need to first check whether column has data, if no data user can alter table. To achieve this condition I wrote the code but it doesn't work:

DROP TABLE IF EXISTS #TABLEDATACOUNT

CREATE TABLE #TABLEDATACOUNT(C BIGINT)

DECLARE @dataCountQuery NVARCHAR(MAX)='SELECT COUNT(*) AS C FROM ['+@DynamicTable+']'

INSERT INTO #TABLEDATACOUNT 
    EXEC sys.sp_executesql @dataCountQuery

IF EXISTS (SELECT * FROM #TABLEDATACOUNT WHERE C>0)
BEGIN
    INSERT INTO @RESULT (ID, [MESSAGE]) 
    VALUES (1, 'Data exists!')

    -- INSERTING NEW COLUMNS
    IF(LEN(@fields) = 0)
        GOTO EXITSP

    DECLARE @index1 BIGINT = 0

    WHILE(@index1 < (SELECT COUNT(*) FROM OPENJSON(@fields)))
    BEGIN
        DECLARE @fieldJson1 NVARCHAR(MAX)=(SELECT [VALUE] FROM OPENJSON(@fields) WHERE [KEY]=@index1)
        DECLARE @fieldName1 NVARCHAR(MAX)=(SELECT [VALUE] FROM OPENJSON(@fieldJson1) WHERE [KEY]='name')
        DECLARE @fieldType1 NVARCHAR(MAX)=(SELECT [VALUE] FROM OPENJSON(@fieldJson1) WHERE [KEY]='type')

        IF((SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME=+'['+@DynamicTable+'] AND COLUMN_NAME='+@fieldName1)=0)
            BEGIN
                DECLARE @insertSql NVARCHAR(MAX)=('ALTER TABLE ['+@DynamicTable+'] ADD ['+@fieldName1+'] '+@fieldType1)
                EXEC sys.sp_executesql @insertSql
                INSERT INTO @RESULT (ID,[MESSAGE]) VALUES (3,'Column inserted')
            END
            
            IF((SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME=+'['+@DynamicTable+'] AND COLUMN_NAME='+@fieldName1)=1)
            BEGIN
            -- Here I need Your support
            -- If Block CHECK table field has no data then user can drop the column
            IF((N'SELECT MAX(['+@fieldName1+']) FROM  ['+@dynamicTableName+']')= 'NULL')
            DECLARE @dropfieldSql NVARCHAR(MAX)=('ALTER TABLE ['+@DynamicTable+'] DROP COLUMN ['+@fieldName1+'])
            EXEC sys.sp_executesql @dropfieldSql
            --INSERT INTO @RESULT (ID,[MESSAGE]) VALUES (3,'Column inserted')
            END
            SET @index1=@index1+1
        END
    END
ELSE
    -- This I managed 

in the above code

Here I need your support

-- If Block CHECK table field has no data then user can drop the column
   IF((N'SELECT MAX(['+@fieldName1+']) FROM  ['+@dynamicTableName+']')= 'NULL')